http://sscheral.atwiki.com/ I struggled to solve some problems so i want to share my solutions and who use these code they once test it and use it. en 2008-08-01T13:48:31+09:00 http://sscheral.atwiki.com/page/SQL%20Date%20Time DECLARE @Date datetime SET @Date = '2001/08/31' SELECT DATEADD(dd,-(DATEPART(dw, @Date) - 1),@Date) AS 'First day of the week' SELECT DATEADD(dd,-(DATEPART(dw, @Date) - 7),@Date) AS 'Last day of the week' SELECT DAY(DATEADD(d, -DAY(DATEADD(m,1,@Date)),DATEADD(m,1,@Date))) AS 'Last day of the month' ============================================================================================================== --To get the first day of month and day name by any date Declare @pInputDate Datetime set @pInputDate=getdate()- 40 set @pInputDate= CAST(CAST(YEAR(@pInputDate) AS VARCHAR(4)) + '/' +                CAST(MONTH(@pInputDate) AS VARCHAR(2)) + '/01' AS DATETIME) --Will give First date of the month --Will give day of the date select @pInputDate AS First_Day_of_mth, datename(dw,@pInputDate) AS Day_Name ============================================================================================================== Hi,      here is the Table: Id    Saledate            Sales 1    2 Jan 2006          100 1    13 Jan 2006        200 1    14 Feb 2006        300 2    3 Feb 2006          150 2    4 Feb 2006           200 3    5 Jan 2006           300 3    13 Feb 2006         400          I need the following output? Id       Jan     Feb     Mar    Apr 1        300     300      0        0 2         0         350      0        0 3        300     400      0       0 --Here is the result: SELECT ID, SUM(CASE WHEN MONTH(saledate) = 1 THEN sales ELSE 0 END) AS 'Jan',    SUM(CASE WHEN MONTH(saledate) = 2 THEN ISNULL(sales,0) ELSE 0 END) AS 'Feb',    SUM(CASE WHEN MONTH(saledate) = 3 THEN ISNULL(sales,0) ELSE 0 END) AS 'Mar',    SUM(CASE WHEN MONTH(saledate) = 4 THEN ISNULL(sales,0) ELSE 0 END) AS 'Apr' FROM sale GROUP BY ID --Here it is shown only for 4 months. You can extend this query for complete year. -- It gives maximum sales in each month select id as ID , MAX(case when month(saledate) =1 then isnull(sales,0) else 0 end) as 'Jan', MAX(case when month(saledate) = 2 then isnull(sales,0) else 0 end) as 'Feb', Max(case when month(saledate) = 3 then isnull(sales,0) else 0 end) as 'Mar', Max(case when month(saledate) = 4 then isnull(sales,0) else 0 end) as 'Apr', Max(case when month(saledate) = 5 then isnull(sales,0) else 0 end) as 'May', Max(case when month(saledate) = 6 then isnull(sales,0) else 0 end) as 'June', Max(case when month(saledate) = 7 then isnull(sales,0) else 0 end) as 'July', Max(case when month(saledate) = 8 then isnull(sales,0) else 0 end) as 'Aug', Max(case when month(saledate) = 9 then isnull(sales,0) else 0 end) as 'Sept', Max(case when month(saledate) = 10 then isnull(sales,0) else 0 end) as 'Oct', Max(case when month(saledate) = 11 then isnull(sales,0) else 0 end) as 'Nov', Max(case when month(saledate) = 12 then isnull(sales,0) else 0 end) as 'Dec' from sale group by month(saledate),id   SELECT     DAY('5/5/2007'),     MONTH('5/1/2007'),     YEAR('5/1/2007'),     DATEPART(DAY, '1/5/2007'),     DATEPART(MONTH, '5/1/2007'),       DATEPART(YEAR, '1/1/2007') Day         MOnth       year        datepart_Day datepart_MOnth datepart_year ======-- ======-- ======-- ======--- ======----- ======---- 5           5           2007        5            5              2007 SELECT     GETDATE() AS local_date,     GETUTCDATE() AS UTC_date local_date              UTC_date ============----- ============----- 2007-05-08 19:12:50.687 2007-05-08 13:42:50.687 SELECT DATEADD(MONTH, 6, GETDATE())AS '6_months_from_now' 6_months_from_now ============----- 2007-11-08 19:12:50.687 ============================================================================================================== declare @datevar datetime select @datevar = getdate() /*Example for getdate() : getting current datetime*/ select getdate() [Current Datetime] /*Example for dateadd : getting date 7 days from current datetime*/ select dateadd(dd, 7, @datevar) [Date 7 days from now] /*Example for datediff : getting no of days passed since 01-01-2004*/ select datediff(dd,'20040101',@datevar) [No of days since 01-01-2004] /*Example for datename : getting month name*/ select datename(mm, @datevar) [Month Name] /*Example for datepart : getting week from date*/ select datepart(wk, @datevar ) [Week No] /*Example for day : getting day part of date*/ select day (@datevar) [Day] /*Example for month : getting month part of date*/ select month(@datevar) [Month] /*Example for year : getting year part of date*/ select year(@datevar) [Year] /* Getting the Day Name like monday tuesday... */ SELECT DATENAME(dw, GETDATE()) -- or /* 0-monday,1-tuesday,2-wednesday ....7-monday,8-tuesday... */ SELECT DATENAME(dw, 0) ============================================================================================================== 2008-08-01T13:48:31+09:00 http://sscheral.atwiki.com/page/Welcome%20to%20Shivshanker%20Page Wiki is a type of websites. You can edit wiki pages easily. You can edit the content with WYSIWYG(HTML)-mode or TEXT-mode or WIKI-mode You can change web site style , If SignIn on page top right bottun. Page Lock is signin user only. Lock-@id is @id user only editable. Lock-admin is admin only editable. 2008-08-01T13:48:27+09:00 http://sscheral.atwiki.com/page/Know%20your%20IDENTITY Know your Identity     Often we create tables that have identity columns. An identity column is a special column in SQL Server that can automatically take on values when an insert operation is done on the table. What if you want to find out whether a table contains an identity column?? SQL Server stores this information in the syscolumns table, but you can access this information in many ways. In this article, we will see the various ways to access information about whether a table has an identity column.   Before we start off with the methods, let's first create a table that has an identity column, like this:   CREATE TABLE samp_test (         colA    INT IDENTITY,         colB    VARCHAR(10) )     Method A   In the first method, we will fetch this information from the syscolumns table. This table contains a column called status that contains various values. If the value in this column contains hexadecimal 80, then it means that the corresponding column contains an identity column. Here is how we can check this:   IF (EXISTS (SELECT name FROM syscolumns WHERE         OBJECT_NAME(id) = 'samp_test' AND status = 0x80))         PRINT 'Table has an identity column' ELSE         PRINT 'Table does not have an identity column'     Method B   In the second method, we will see whether a table has an identity column using the COLUMNPROPERTY function. This function takes an argument IsIdentity that indicates whether the column is an identity column. Here is how we can do the check using this function:   IF (EXISTS (SELECT myTemp.IsIdentity FROM         (SELECT IsIdentity=COLUMNPROPERTY(id, name, 'IsIdentity')                FROM syscolumns WHERE OBJECT_NAME(id) = 'samp_test') AS myTemp         WHERE myTemp.IsIdentity = 1))         PRINT 'Table has an identity column' ELSE         PRINT 'Table does not have an identity column'     This method is slightly convoluted since the COLUMNPROPERTY function takes the name of the column as the parameter. Thus, if we want to make a generic sort of a call, we need to iterate through each column of a table using the syscolumns table and then make a call to the COLUMNPROPERTY function. Finally we then run an EXISTS check over this derived table to check for identity.   Method C   In the final method, we will use the OBJECTPROPERTY function to check whether a table has an identity column. Here is how we can do the check using this function:   IF (OBJECTPROPERTY(OBJECT_ID('samp_test'), 'TableHasIdentity') = 1)         PRINT 'Table has an identity column' ELSE         PRINT 'Table does not have an identity column'     This is the easiest of the lot. The OBJECTPROPERTY function takes as parameter the name of the object to check (a table in this case) and then the name of the property. We use the OBJECT_ID function to get the ID of the object. We then use the TableHasIdentity property to check if the table has an identity column. One difference between this method and the others is that this method does not give the name of the column which is the identity column, which is possible using the other two methods. 2008-08-01T13:47:08+09:00 http://sscheral.atwiki.com/page/How%20to%20retrieve%20the%20last%20day%20of%20the%20month%20....%20Or%20Last%20date%20in%20the%20week How to retrieve the last day of the month .... Or Last date in the week? Answer: To add a addendum ... how can I find out the number of days in a given month. eg. If I were to give you '2003-03-01' I should get 31. If you feel its a bit tricky in nature then ... See the solutions below ... DECLARE @Date datetime SET @Date = '2000/02/1' SELECT DATEADD(dd,-(DATEPART(dw, @Date) - 1),@Date) AS 'First day of the week' SELECT DATEADD(dd,-(DATEPART(dw, @Date) - 7),@Date) AS 'Last day of the week' SELECT DAY(DATEADD(d, -DAY(DATEADD(m,1,@Date)),DATEADD(m,1,@Date))) AS 'Last day of the month' Since the Last Day would yield you the number of days in a month then it anwers my addendum question also. Some more solutions for the number of days in a month are below: DECLARE @d DATETIME SET @d = '2003-02-1' select datepart(dd, dateadd(dd, -(datepart(dd, dateadd(mm, 1, @d))),dateadd(mm, 1, @d))) AS 'Last day of the month' GO DECLARE @d DATETIME SET @d = '2000-02-1' SELECT CASE WHEN MONTH(@d) = 1 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 2 　　　　　 THEN CASE WHEN (YEAR(@d) % 4 = 0 AND YEAR(@d) % 100 <> 0) OR 　　　　　　　　　　　　　 YEAR(@d) % 400 = 0 　　　　　　　　　　 THEN 29 　　　　　　　　　　 ELSE 28 　　　　　 END 　　　　　 WHEN MONTH(@d) = 3 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 4 　　　　　 THEN 30 　　　　　 WHEN MONTH(@d) = 5 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 6 　　　　　 THEN 30 　　　　　 WHEN MONTH(@d) = 7 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 8 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 9 　　　　　 THEN 30 　　　　　 WHEN MONTH(@d) = 10 　　　　　 THEN 31 　　　　　 WHEN MONTH(@d) = 11 　　　　　 THEN 30 　　　　　 WHEN MONTH(@d) = 12 　　　　　 THEN 31 　　　 END AS 'Last day of the month' Whew .... That's a mess to understand ... Believe me they work ... :-) ... There are hundreds of way the SQL Selects can be done ... This is just few of them ... And one more ... SELECT DAY(DATEADD(DAY,-1,DATEADD(MONTH,1,DATEADD(DAY,1-DAY(@d),@d)))) AS 'Last day of the month' Note: Some of the tips and tricks are subjected to some specific SQL Server settings hence use them with loads of care. 2008-06-29T20:42:02+09:00 http://sscheral.atwiki.com/page/ASP%20Databound Protected Sub dgSurveys_RowDataBound(ByVal sender As Object, ByVal e As System.Web.UI.WebControls.GridViewRowEventArgs) Handles dgSurveys.RowDataBound If e.Row.RowType = DataControlRowType.DataRow Then Dim hyp As HyperLink = CType(e.Row.Cells(0).Controls(0), HyperLink) Dim url As String = hyp.NavigateUrl Dim split1 As String() = url.Split("?") Dim finalUrl As String = split1(0) If split1.Length > 1 Then finalUrl &= "?" Dim split2 As String() = split1(1).Split("&") Dim query As String Dim isFirstElement As Boolean = True For Each query In split2 If isFirstElement = False Then finalUrl &= "&" End If If query.Split("=").Length > 1 Then finalUrl &= query.Split("=")(0) & "=" & Server.UrlEncode(query.Split("=")(1)) Else finalUrl = finalUrl.Substring(0, finalUrl.Length - 1) finalUrl &= Server.UrlEncode("&" & query) End If isFirstElement = False Next End If hyp.NavigateUrl = finalUrl If DirectCast(e.Row.FindControl("lblDueCross"), Label).Text = "1" Then e.Row.Cells.Item(3).ForeColor = Drawing.Color.Red End If dgSurveys.DataKeys(e.Row.RowIndex).Item(2).ToString() 'Dim strKeyword As String = dgSurveys.DataKeys(e.Row.RowIndex).Item(14).ToString 'If strKeyword = "Gas Warm Air Furnace by Efficiency, State, Configuration Report" Then 'End If Dim tempStr As String = DirectCast(e.Row.FindControl("lblFreqType"), Label).Text ' Code to Disable if the selected company did not fill ' the monthly survey corresponding to the Quarterly survey If ChangeDBNullToEmptyString(Right(tempStr, (tempStr.Length - 1)).ToString) "" Then If Left(tempStr, 1) = "2" Then ' Check Whether Survey is Quarterly or not Dim count As Int16 Dim t As String = dgSurveys.DataKeys(e.Row.RowIndex).Values(2).ToString Dim strsql As New System.Text.StringBuilder Try strsql.Append("GetThreeMonthlySurveyID ") strsql.Append(PrepareString(t) & COMMA) strsql.Append(PrepareString(Right(tempStr, (tempStr.Length - 1)).ToString)) sqlcmd.CommandTimeout = 1000 count = getSingleValue(sqlcmd, strsql.ToString) Catch ex As Exception End Try If count > 0 Then 'e.Row.Cells.Item(0).Enabled = False e.Row.Cells.Item(0).Attributes.Add("style", "cursor:hand") Dim txt As String = CType(e.Row.Cells.Item(0).Controls(0), HyperLink).Text e.Row.Cells.Item(0).Controls.Remove(e.Row.Cells.Item(0).Controls(0)) e.Row.Cells.Item(0).Text = txt 'e.Row.Cells.Item(0).CssClass = "GridGray" e.Row.Cells.Item(0).ForeColor = Drawing.Color.Gray e.Row.Cells.Item(0).Attributes.Add("onclick", "alert('Please fill out the corresponding monthly survey first.')") e.Row.Cells.Item(4).Enabled = False e.Row.Cells.Item(6).Enabled = False e.Row.Cells.Item(5).Text = "Please fill out the corresponding monthly survey first" e.Row.Cells.Item(5).ForeColor = Drawing.Color.Red End If End If End If Dim tblCellControl As System.Web.UI.WebControls.ImageButton = e.Row.Cells.Item(e.Row.Cells.Count - 1).FindControl("img1") tblCellControl.Attributes.Add("onclick", "return getConfirm('Please note that uploading the Excel data will overwrite any data entered in the online form.\nDo you want to proceed?');") 'Dim tblCellControl1 As System.Web.UI.WebControls.ImageButton = e.Row.Cells.Item(e.Row.Cells.Count - 1).FindControl("imgDownload") 'tblCellControl1.Attributes.Add("onclick", "return excelDownload();") End If End Sub 2008-05-11T19:04:16+09:00 http://sscheral.atwiki.com/page/ASP.NET%20Differences Difference between Convert.ToInt32 and int.Parse Both(Convert.ToInt32 and int.Parse) will return the same resule in most of the cases. But null is handled differently. Consider the following example&string strCount="32"; int count1 = Convert.ToInt32(strCount); int count2 = int.Parse(strCount); If you print the result it will be same ie 32. If suppose the string is the null (see the example below), Convert.ToInt32 will return zero. but the int.Parse will throw ArgumentNullException error.string strCount=null; int count1 = Convert.ToInt32(strCount); int count2 = int.Parse(strCount); // Error If you don't assign (initialize) null to the strCount the code will not compile. Because in C# variable must be initialized before use. "Int32" and "int" Well, when i searched msn, i found most of the people said both are same, the only difference is coloring in the IDE.(ha!!). But one guy from microsoft pointed out one difference that u cannot use Int32 in enum. which will result in compiler error(Type byte, sbyte, short, ushort, int, uint, long, or ulong expected). Quite intersting but microsft didn't accept this as bug, they said it is by design.. This is only with C# and in VB.NET works fine. Dataset Vs DataReader To better improve the performance of a solution, we have to understand the DataSet and DataReader and they have to be used correctly in the places they needed. Let see how they work... DataReader Datareader is like a forward only recordset. It fetches one row at a time so very less Network Cost compare to DataSet(Fetches all the rows at a time). DataReader is readonly so we cannot do any transaction on them. DataReader will be the best choice where we need to show the data to the user which requires no transaction ie reports. Due to DataReader is forward only we cannot fetch the data randomly. .NET Dataproviders optimizes the datareaders to handle the huge amount of data. DataSet DataSet is always a bulky object that requires lot of memory space compare to DataReader. We can say the dataset as a small database coz it stores the schema and data in the application memory area. DataSet fetches all data from the datasource at a time to its memory area. So we can traverse through the object to get required data like qureying database. The dataset maintains the relationships among the datatables inside it. We can manipulate the realational data as XML using dataset.We can do transactions (insert/update/delete) on them and finally the modifications can be updated to the actual database. This provides impressive flexibility to the application but with the cost of memory space. DataSet maintains the original data and the modified data seperately which requires more memory space. If the amount of data in the dataset is huge then it will reduce the applications performance dramatically. The following points will improve the performane of a dataset... 1. Don't use the commandbuilder to generate the sql statements. Though it reduces the development time the query generated by the command builder will not be always as required. For example To update the details of an author table the command builder will generate a query like this ... Query generated by CommandBuilder UPDATE authors SET au_id = ?, au_fname = ?, au_lname = ?, phone = ?, zip = ?, state = ?, city = ?, address = ? WHERE (au_id = ?) AND (address = ? OR ? IS NULL AND address IS NULL) AND (au_fname = ?) AND (au_lname = ?) AND (city = ? OR ? IS NULL AND city IS NULL) AND (phone = ?) AND (state = ? OR ? IS NULL AND state IS NULL) AND (zip = ? OR ? IS NULL AND zip IS NULL) But we can write much more efficient query than the above like this ..UPDATE authors SET au_id = ?, au_fname = ?, au_lname = ?, phone = ?, zip = ?, state = ?, city = ?, address = ? WHERE (au_id = ?) 2. Always select the columns required in the quries. Don't use "select * from <table_name>". Take an example of authors table which has the author id , name, address, image. For showning the author name,address if we use select * then the image column also fetched from the database which requires more memory and NetWork Cost will be more due the amount of data. This will reduce the applications performance. 3. Always try to use the parameter collection for the stored procedures. We can execute the stored proceduers in two ways. a. we can create a string as a query and can execute it. Ex "getAuthor(7689)". b. we can create a command object. Assign the Stored Procedure name to the commandtext property. Specify the commandtype as stored procedure. Create a parameter for the value passed to the SP and execute. Ex:SqlCommand sqlcmd = new SqlCommand(); sqlcmd.CommandText="getAuthors"; sqlcmd.CommandType= CommandType.StoredProcedure; SqlParameter sqlparam = new SqlParameter ("@au_id",SqlDbType.Int); sqlparam.Value = 7689; sqlcmd.Parameters.Add(sqlparam); sqlcmd.Connection= con; sqlcmd.ExecuteReader(); There are lot of difference between the way the two quries executed. The first query will be sent to the database server as a string though we think we are passing the author id as int. The database server will parse the query and will determine the datatype of the parameter. This extra processing will increase the execution time. But while executing the second query the native datatype of the parameter is sent to the database server as network packets throuh RPC. Difference between Convert.ToInt32 and int.Parse Both(Convert.ToInt32 and int.Parse) will return the same resule in most of the cases. But null is handled differently. Consider the following example& string strCount="32"; int count1 = Convert.ToInt32(strCount); int count2 = int.Parse(strCount); If you print the result it will be same ie 32. If suppose the string is the null (see the example below), Convert.ToInt32 will return zero. but the int.Parse will throw ArgumentNullException error. string strCount=null; int count1 = Convert.ToInt32(strCount); int count2 = int.Parse(strCount); // Error If you don't assign (initialize) null to the strCount the code will not compile. Because in C# variable must be initialized before use. 2008-04-19T00:00:35+09:00 http://sscheral.atwiki.com/page/Links http://jslint.com/ http://www.glasshaus.com/samplechapters/1051/default.asp http://www.w3schools.com 2008-01-15T09:43:09+09:00 http://sscheral.atwiki.com/page/SQL%20UNION%2C%20SQL%20INTERSECT%2C%20SQL%20EXCEPT%2C%20SQL%20EXISTS%20and%20SQL%20CASE%20for%20Beginners SQL UNION, SQL INTERSECT, SQL EXCEPT, SQL EXISTS and SQL CASE for Beginners   SQL UNION, SQL INTERSECT, SQL EXCEPT, SQL EXISTS and SQL CASE Table1     C1 C2 1 A B 2 A C 3 A D Table2   C1 C2 1 A B 2 A C 3 A E SQL UNION The purpose of the SQL UNION command is to combine the results of two queries together. In this respect, UNION is somewhat similar to JOIN in that they are both used to related information from multiple tables. One restriction of UNION is that all corresponding columns need to be of the same data type. Also, when using UNION, only distinct values are selected (similar to SELECT DISTINCT). The purpose of the SQL UNION ALL command is also to combine the results of two queries together. The difference between UNION ALL and UNION is that, while UNION only selects distinct values, UNION ALL selects all values. The syntax is as follows: [SQL Statement 1] UNION [ALL] [SQL Statement 2]   The following are basic rules for combining the result sets of two queries by using UNION: ·             The number and the order of the columns must be the same in all queries. ·             The data types must be compatible.   SELECT C1,C2 FROM T1 UNION SELECT C1,C2 FROM T2   SELECT C1,C2 FROM T1 UNION ALL SELECT C1,C2 FROM T2 Result:     C1 C2 1 A B 2 A C 3 A D 4 A E Result:   C1 C2 1 A B 2 A C 3 A D 4 A B 5 A C 6 A e       SQL INTERSECT Similar to the UNION command, INTERSECT also operates on two SQL statements. The difference is that, while UNION essentially acts as an OR operator (value is selected if it appears in either the first or the second statement), the INTERSECT command acts as an AND operator (value is selected only if it appears in both statements). Returns distinct values by comparing the results of two queries. INTERSECT returns any distinct values that are returned by both the query on the left and right sides of the INTERSECT operand. The basic rules for combining the result sets of two queries that use INTERSECT are the following: ·             The number and the order of the columns must be the same in all queries. ·             The data types must be compatible. The syntax is as follows: [SQL Statement 1] INTERSECT [SQL Statement 2]   SELECT C1,C2 FROM T1 INTERSECT SELECT C1,C2 FROM T2 Result:   C1 C2 1 A B 2 A C Note: INTERSECT will work only in SQL 2005. SQL EXCEPT The EXCEPT (MINUS) operates on two SQL statements. It takes all the results from the first SQL statement, and then subtract out the ones that are present in the second SQL statement to get the final answer. If the second SQL statement includes results not present in the first SQL statement, such results are ignored. EXCEPT returns any distinct values from the left query that are not also found on the right query. The basic rules for combining the result sets of two queries that use EXCEPT are the following: ·             The number and the order of the columns must be the same in all queries. ·             The data types must be compatible. The syntax is as follows: [SQL Statement 1] EXCEPT [SQL Statement 2]     SELECT C1,C2 FROM T1 EXCEPT SELECT C1,C2 FROM T2   Result:   C1 C2     2007-11-30T11:21:28+09:00 http://sscheral.atwiki.com/page/SQL%20Parse%20Array%20Function Yet another version of the function to return a table from a delimitted string of values if exists (select * from dbo.sysobjects where id = object_id(N'[dbo].[fn_ParseCSVString]') and xtype in (N'FN', N'IF', N'TF')) drop function [dbo].[fn_ParseCSVString] GO create function fn_ParseCSVString ( @CSVString varchar(8000) , @Delimiter varchar(10) ) returns @tbl table (s varchar(1000)) as /* select * from dbo.fn_ParseCSVString ('qwe,c,rew,c,wer', ',c,') */ begin declare @i int , @j int select @i = 1 while @i <= len(@CSVString) begin select @j = charindex(@Delimiter, @CSVString, @i) if @j = 0 begin select @j = len(@CSVString) + 1 end insert @tbl select substring(@CSVString, @i, @j - @i) select @i = @j + len(@Delimiter) end return end 2007-09-27T11:46:14+09:00 http://sscheral.atwiki.com/page/Operators%20T-SQL%3A Operators (T-SQL) An operator is a symbol specifying an action that is performed on one or more expressions. Microsoft® SQL Server™ uses these operator categories: Arithmetic operators Assignment operator Bitwise operators Comparison operators Logical operators String concatenation operator Unary operators Arithmetic Operators Arithmetic operators perform mathematical operations on two expressions of any of the data types of the numeric data type category. For more information about data type categories, see Transact-SQL Syntax Conventions. Operator Meaning + (Add) Addition. - (Subtract) Subtraction. * (Multiply) Multiplication. / (Divide) Division. % (Modulo) Returns the integer remainder of a division. For example, 12 % 5 = 2 because the remainder of 12 divided by 5 is 2.   The + and - operators can also be used to perform arithmetic operations on datetime and smalldatetime values. For information about the precision and scale of the result of an arithmetic operation, see Precision, Scale, and Length. Assignment Operator Transact-SQL has one assignment operator, the equals sign (=). In this example, the @MyCounter variable is created. Then, the assignment operator sets @MyCounter to a value returned by an expression. DECLARE @MyCounter INT SET @MyCounter = 1    The assignment operator (=) can also be used to establish the relationship between a column heading and the expression defining the values for the column. This example displays two column headings named FirstColumnHeading and SecondColumnHeading. The string xyz is displayed in the FirstColumnHeading column heading for all rows. Then, each product ID from the Products table is listed in the SecondColumnHeading column heading. USE Northwind GO SELECT FirstColumnHeading = 'xyz',        SecondColumnHeading = ProductID FROM Products GO    Bitwise Operators Bitwise operators perform bit manipulations between two expressions of any of the data types of the integer data type category. Operator Meaning & (Bitwise AND) Bitwise AND (two operands). | (Bitwise OR) Bitwise OR (two operands). ^ (Bitwise Exclusive OR) Bitwise exclusive OR (two operands).   The operands for bitwise operators can be any of the data types of the integer or binary string data type categories (except for the image data type), with the exception that both operands cannot be any of the data types of the binary string data type category. The table shows the supported operand data types. Left operand Right operand binary int, smallint, or tinyint bit int, smallint, tinyint, or bit int int, smallint, tinyint, binary, or varbinary smallint int, smallint, tinyint, binary, or varbinary tinyint int, smallint, tinyint, binary, or varbinary varbinary int, smallint, or tinyint   Comparison Operators Comparison operators test whether or not two expressions are the same. Comparison operators can be used on all expressions except expressions of the text, ntext, or image data types. Operator Meaning = (Equals) Equal to. > (Greater Than) Greater than. < (Less Than) Less than. >= (Greater Than or Equal To) Greater than or equal to. <= (Less Than or Equal To) Less than or equal to. <> (Not Equal To) Not equal to. != (Not Equal To) Not equal to (not SQL-92 standard). !< (Not Less Than) Not less than (not SQL-92 standard). !> (Not Greater Than) Not greater than (not SQL-92 standard).   The result of a comparison operator has the Boolean data type, which has three values: TRUE, FALSE, and UNKNOWN. Expressions that return a Boolean data type are known as Boolean expressions. Unlike other SQL Server data types, a Boolean data type cannot be specified as the data type of a table column or variable, and cannot be returned in a result set. When SET ANSI_NULLS is ON, an operator that has one or two NULL expressions returns UNKNOWN. When SET ANSI_NULLS is OFF, the same rules apply, except an equals operator returns TRUE if both expressions are NULL. For example, NULL = NULL returns TRUE if SET ANSI_NULLS is OFF. Expressions with Boolean data types are used in the WHERE clause to filter the rows that qualify for the search conditions and in control-of-flow language statements such as IF and WHILE, for example: USE Northwind GO DECLARE @MyProduct int SET @MyProduct = 10 IF (@MyProduct <> 0)     SELECT *     FROM Products     WHERE ProductID = @MyProduct GO    Logical Operators Logical operators test for the truth of some condition. Logical operators, like comparison operators, return a Boolean data type with a value of TRUE or FALSE. Operator Meaning ALL TRUE if all of a set of comparisons are TRUE. AND TRUE if both Boolean expressions are TRUE. ANY TRUE if any one of a set of comparisons are TRUE. BETWEEN TRUE if the operand is within a range. EXISTS TRUE if a subquery contains any rows. IN TRUE if the operand is equal to one of a list of expressions. LIKE TRUE if the operand matches a pattern. NOT Reverses the value of any other Boolean operator. OR TRUE if either Boolean expression is TRUE. SOME TRUE if some of a set of comparisons are TRUE.   For more information about logical operators, see the specific logical operator topic. String Concatenation Operator The string concatenation operator allows string concatenation with the addition sign (+), which is also known as the string concatenation operator. All other string manipulation is handled through string functions such as SUBSTRING. By default, an empty string is interpreted as an empty string in INSERT or assignment statements on data of the varchar data type. In concatenating data of either the varchar, char, or text data types, the empty string is interpreted as an empty string. For example, ‘abc’ + ‘‘ + ‘def’ is stored as ‘abcdef’. However, if the sp_dbcmptlevel compatibility level setting is 65, empty constants are treated as a single blank character and ‘abc’ + ‘‘ + ‘def’ is stored as ‘abc def’. For more information about the interpretation of empty strings, see sp_dbcmptlevel. Unary Operators Unary operators perform an operation on only one expression of any of the data types of the numeric data type category. Operator Meaning + (Positive) Numeric value is positive. - (Negative) Numeric value is negative. ~ (Bitwise NOT) Returns the ones complement of the number.   The + (Positive) and - (Negative) operators can be used on any expression of any of the data types of the numeric data type category. The ~ (Bitwise NOT) operator can be used only on expressions of any of the data types of the integer data type category. Operator Precedence When a complex expression has multiple operators, operator precedence determines the sequence in which the operations are performed. The order of execution can significantly affect the resulting value. Operators have these precedence levels. An operator on higher levels is evaluated before an operator on a lower level: + (Positive), - (Negative), ~ (Bitwise NOT) * (Multiply), / (Division), % (Modulo) + (Add), (+ Concatenate), - (Subtract) =, >, <, >=, <=, <>, !=, !>, !< (Comparison operators) ^ (Bitwise Exlusive OR), & (Bitwise AND), | (Bitwise OR) NOT AND ALL, ANY, BETWEEN, IN, LIKE, OR, SOME = (Assignment) When two operators in an expression have the same operator precedence level, they are evaluated left to right based on their position in the expression. For example, in the expression used in the SET statement of this example, the subtraction operator is evaluated before the addition operator. DECLARE @MyNumber int SET @MyNumber = 4 - 2 + 27 -- Evaluates to 2 + 27 which yields an expression result of 29. SELECT @MyNumber    Use parentheses to override the defined precedence of the operators in an expression. Everything within the parentheses is evaluated first to yield a single value before that value can be used by any operator outside of the parentheses. For example, in the expression used in the SET statement of this example, the multiplication operator has a higher precedence than the addition operator, so it gets evaluated first; the expression result is 13. DECLARE @MyNumber int SET @MyNumber = 2 * 4 + 5 -- Evaluates to 8 + 5 which yields an expression result of 13. SELECT @MyNumber    In the expression used in the SET statement of this example, the parentheses causes the addition to be performed first; the expression result is 18. DECLARE @MyNumber int SET @MyNumber = 2 * (4 + 5) -- Evaluates to 2 * 9 which yields an expression result of 18. SELECT @MyNumber    If an expression has nested parentheses, the most deeply nested expression is evaluated first. This example contains nested parentheses, with the expression 5 - 3 in the most deeply nested set of parentheses. This expression yields a value of 2. Then, the addition operator (+) adds this result to 4, which yields a value of 6. Finally, the 6 is multiplied by 2 to yield an expression result of 12. DECLARE @MyNumber int SET @MyNumber = 2 * (4 + (5 - 3) ) -- Evaluates to 2 * (4 + 2) which further evaluates to 2 * 6, and -- yields an expression result of 12. SELECT @MyNumber    See Also Functions 2007-09-26T07:16:05+09:00