示例2:布尔表达式中带有变量的IF语句(Example 2: IF Statement with a variable in a Boolean expression) In the following example, we use a variable in the Boolean expression to execute the statement based on the condition. For example, if a student obtained more than 80% marks, he passes an ...
IF...THEN statements are the simplest form of IF. The statements between THEN and END IF are executed only if the condition evaluates to TRUE. In the following example, an IF...THEN statement is used to test for and to display those employees who have a commission. DECLARE v_empno emp....
某工具在运行过程中,会产生下面的SQL进行查询,WHERE后跟了N多个条件: mysql> select * from order_line where (ol_w_id = '1' and ol_d_id...这里说的N多个,是指总共有10000个OR条件,这条SQL的长度大概将近800KB。...相当于做了1万次索引列等值条件查询。 查询效率提升非常显著。 进一步优化 线上生产...
If you change the value of the input_film_id variable to some value that exists in the film table like 100, you will not see any message. 2) PL/pgSQL if-then-else statement The if...then...else statement executes the statements in the if branch if the condition evaluates to true;...
Changing the value of any variable will affect the result, as shown below. Example: IF ELSE Statement Copy DECLARE @mySalary INT = 5000, @avgSalary = 6000; IF @mySalary > @avgSalary PRINT 'My Salary is above the average salary.'; ELSE PRINT ' My Salary is less than the average...
3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 状态图 BeginnerVariableCreationExpressionCreationIfStatement 通过以上步骤,初学者可以学会如何在MySQL select语句中创建表达式并赋值给变量,然后使用IF语句进行判断。希望这篇文章对你有所帮助,加油!
SQL 过程中的 IF 语句 可使用 IF 语句来根据条件满足状态而有条件进入某个逻辑。IF 语句在逻辑上等价于带有搜索式 CASE 语句 WHEN 子句的 CASE 语句。 IF 语句支持使用可选 ELSE IF 子句和缺省 ELSE 子句。END IF 子句是指示语句结尾所必需的。 以下是包含 IF 语句的过程的示例:...
{ sql_statement | statement_block } 使用语句块定义的任何 Transact-SQL 语句或语句分组。 除非使用了语句块,IF否则或ELSE条件只能影响一个 Transact-SQL 语句的性能。 若要定义语句块,请使用流控制关键字BEGIN和END。 注解 IF...ELSE可以在批处理、存储过程和即席查询中使用构造。 在存储过程中使用此构造时,通...
SqlParser.Parser.Internals Microsoft.SqlServer.Management.SqlParser.SqlCodeDom Microsoft.SqlServer.Management.SqlParser.SqlCodeDom CreateIndexKeyList CreateIndexStart CreateTypeStatementInfo CreateUserStatementFactory CursorDefinitionInfo DdlTargetObjectType DmlTarget Functio...
Learn more about the Microsoft.SqlServer.Management.SqlParser.SqlCodeDom.SqlIfElseStatement.FalseStatement in the Microsoft.SqlServer.Management.SqlParser.SqlCodeDom namespace.