When I have just CASE statement, it works. When I have just the IF statement, it works. When I have both or 2 CASE statements, it pukes. Can anyone shine some light on this? Can there only be 1 conditional in th
You can use one or more tables separated by a comma to include various conditions using a WHERE clause, but the WHERE clause is an optional part of the SELECT command. 您可以使用WHERE子句来使用一个或多个用逗号分隔的表来包含各种条件,但是WHERE子句是SELECT命令的可选部分。 You can specify any ...
则出现mysqlUnknowncolumn'op_task.task_no'in'whereclause'找不到这个task_no字段的错误 mysql版本为5.6,查出表A,所有数据,当表A的task_type=1时,统计表B中task_no和表A的task_no相同的数量,否则统计表C中task_no和表A的task_no相同的数量, 表A为: CREATETABLE`op_task`( idint(10)unsignedNOTNULLAUTO...
We compare the value of the case_expression with when_expression in each WHEN clause e.g., when_expression_1, when_expression_2, etc. If the value of the case_expression and when_expression_n are equal, the commands in the corresponding WHEN branch executes. In case none of the when_...
You use the simple CASE statement to check the value of an expression against a set of unique values. The case_expressioncan be any valid expression. The case_expression is compared with when_expression in each WHEN clause e.g., when_expression_1 and when_expression_2 . If the values of...
可以看到通过select出的字段是覆盖索引,MySQL底层使用了索引优化。在看另一个case: 代码语言:javascript 代码运行次数:0 运行 AI代码解释EXPLAIN select * from employees where name > 'zzz';对于上面的这两种 name>'a' 和 name>'zzz'的执行结果, mysql最终是否选择走索引或者一张表涉及多个索引, mysql最终如何...
J:firstmatch(tb_name):5.6.x开始引入的优化子查询的新特性之一,常见于where字句含有in()类型的子查询。如果内表的数据量比较大,就可能出现这个。 K:loosescan(m..n):5.6.x之后引入的优化子查询的新特性之一,在in()类型的子查询中,子查询返回的可能有重复记录时,就可能出现这个。
Because of the regression still present in the MySQL 8.0.14, 8.0.15, and 8.0.16 releases, importing partitioned tables from MySQL 8.0.14, 8.0.15, or 8.0.16 to MySQL 8.0.17 is not supported on case-sensitive file systems where lower_case_table_names=1. Attempting to do so results in...
In this case, every such column must be limited to a single value in the WHERE clause, and all such limiting conditions must be joined by logical AND, as shown here: mysql> DROP TABLE IF EXISTS mytable; mysql> CREATE TABLE mytable ( -> id INT UNSIGNED NOT NULL PRIMARY KEY, -> a...
Re: CASE and IF in WHERE clause 4717 m z May 20, 2009 11:38AM Re: CASE and IF in WHERE clause 7481 Peter Brawley May 20, 2009 11:57AM Re: CASE and IF in WHERE clause 4850 m z May 22, 2009 02:48PM Sorry, you can't reply to this topic. It has been closed.Content rep...