TheCASE expressionis used to build IF … THEN … ELSE statements into your Microsoft SQL Server T-SQL code. CASE is used within a SQL statement, such as SELECT or UPDATE. Don’t mistake CASE for theIF ELSEcontrol of flow construct, which is used to evaluate the conditional execution of ...
A. Use a SELECT statement with a simple CASE expression Within aSELECTstatement, a simpleCASEexpression allows for only an equality check; no other comparisons are made. The following example uses theCASEexpression to change the display of product line categories to make them more understandable. ...
Whenever youinsert a new row in a SQL Server tablethat contains default values, you may want toreturn the newly inserted rowto the user, along with the default value generated. However while doing a plain INSERT statement, all you get is the total number of rows affected. Here’s an exa...
Internally SQL Server converts the statement into the CASE statement and executes. We can check it using the actual execution plan of a query. Execute the query from Example 6 with an Actual execution plan. In the actual execution plan, look at the properties of Compute Scalar. You can see...
The example creates CLR function len_s. Before the function is created, the assembly SurrogateStringFunction.dll is registered in the local database. Applies to: SQL Server 2008 (10.0.x) SP 1 and later versions. SQL 复制 DECLARE @SamplesPath NVARCHAR(1024); -- You may have to modify th...
The example creates CLR function len_s. Before the function is created, the assembly SurrogateStringFunction.dll is registered in the local database. Applies to: SQL Server 2008 (10.0.x) SP 1 and later versions. SQL 複製 DECLARE @SamplesPath NVARCHAR(1024); -- You may have to modify th...
The following example passes a command string to a remote server. It creates a linked server SeattleSales that points to another instance of SQL Server and executes a DDL statement (CREATE TABLE) against that linked server. SQL Copy EXECUTE sp_addlinkedserver 'SeattleSales', 'SQL Server'; ...
Conditional statements are very prevalent when working with databases. For example, we can use the CASE keyword in SQL to provide a set of evaluated conditions. We can then execute the code block if a given statement is true. A case statement is similar to a nested if…else block which al...
Case expressions may only be nested to level 10. Note that when running a CASE expression against a linked server, the optimizer on the other side may expand this to a nested CASE expression and cause this issue, even though it’s not what you wrote; seethis examplefrom Paul White. ...
Sql Server 会有以下方法来查找您需要的数据记录: 1. 【Table Scan】:遍历整个表,查找所匹配的记录行。这个操作将会一行一行的检查,当然,效率也是最差的。 2. 【Index Scan】:根据非聚集索引,扫描索引的全部记录,查找所匹配的记录行,匹配的条件可从查询计划的Argument列中看到。比第一种方式的查找范围要小(B+...