MySQL 中 delete 语句的子查询限制 from student); [Err] 1093 - You can't specify target table 'student' for update in FROM clause 描述: 如果子查询的...解决方法: 通过给 from 子句中的结果集起别名。...student m where m.id = 1; [Err] 1064 - You have an error in your SQL syntax; ...
MySQL 中 delete 语句的子查询限制 from student); [Err] 1093 - You can't specify target table 'student' for update in FROM clause 描述: 如果子查询的...student m where m.id = 1; [Err] 1064 - You have an error in your SQL syntax; 描述: delete from table 这样的句子中 3.9K30 mysq...
In this syntax, `CASE` checks each condition sequentially and returns the corresponding result for the first true condition; if none are true, it returns the `ELSE` result. Examples 1. Basic Case Usage SELECTproduct_name,CASEWHENstock_quantity>0THEN'In Stock'ELSE'Out of Stock'ENDASstock_stat...
For the first syntax, case_value is an expression. This value is compared to the when_value expression in each WHEN clause until one of them is equal. When an equal when_value is found, the corresponding THEN clause statement_list executes. If no when_value is equal, the ELSE clause ...
The firstCASEsyntax returns theresultfor the first ***value***=***compare_value***comparison that is true. The second syntax returns the result for the first condition that is true. If no comparison or condition is true, the result afterELSEis returned, orNULLif there is noELSEpart. ...
The following illustrates the syntax of the searched CASE statement: CASE WHEN condition_1 THEN commands WHEN condition_2 THEN commands ... ELSE commands END CASE; MySQL evaluates each condition in the WHEN clause until it finds a condition whose value is TRUE, then corresponding commands in the...
The following illustrates the syntax of the searched CASE statement: 1 2 3 4 5 6 CASE WHEN condition_1 THEN commands WHEN condition_2 THEN commands ... ELSE commands END CASE; MySQL evaluates each condition in the WHEN clause until it finds a condition whose value is TRUE , then corresp...
If no conditions are true, it will return the value in the ELSE clause. If there is no ELSE part and no conditions are true, it returns NULL. Syntax CASE WHENcondition1THENresult1 WHENcondition2THENresult2 WHENconditionNTHENresultN
[mysql]> helpcaseoperator; #case的第二种基本用法24Name: 'CASE OPERATOR'25Description:26Syntax:27CASE value WHEN [compare_value] THEN result [WHEN [compare_value] THEN28result ...] [ELSE result] END2930CASE WHEN [condition] THEN result [WHEN [condition] THEN result ...]31[ELSE result] ...
For the first syntax, case_value is an expression. This value is compared to the when_value expression in each WHEN clause until one of them is equal. When an equal when_value is found, the corresponding THEN clause statement_list executes. If no when_value is equal, the ELSE clause ...