and you can use it almost anywhere a single column value or literal is legal. If the subquery returns 0 rows then the value of scalar subquery expression in NULL and if the subquery returns more than one row then MySQL returns an error. ...
You can use TABLE in a scalar IN, ANY, or SOME subquery provided the table contains only a single column. If t2 has only one column, the statements shown previously in this section can be written as shown here, in each case substituting TABLE t2 for SELECT s1 FROM t2: ...
and the subquery returns either a single value as a result of a row set. Hence, the primary use of subquery can be to compute an instant value for another query to be executed.
【A limitation on UPDATE and DELETE statements that use a subquery to modify a single table is that the optimizer does not use semijoin or materialization subquery optimizations. As a workaround, try rewriting them as multiple-table UPDATE and DELETE statements that use a join rather than a su...
创建方式2使用AS subquery 选项,将创建表和插入数据结合起来指定的列和子查询中的列要一一对应通过列名和默认值定义列CREATE TABLE emp1 AS SELECT * FROM employees;CREATE TABLE emp2 AS SELECT * FROM employees WHERE 1=2; -- 创建的emp2是空表CREATE TABLE dept80...
使用AS subquery 选项,将创建表和插入数据结合起来 CREATE TABLE 表名[(column, column, ...)] AS subquery; 指定的列和子查询中的列要一一对应 通过列名和默认值定义列 CREATE TABLE dept80 AS SELECT employee_id, last_name, salary*12 ANNSAL, hire_date FROM employees WHERE department_id = 80;...
1、MySQL subquery within a WHERE clause 1.1、MySQL subquery with comparison operators You can use comparison operators e.g., =, >, <, etc., to compare a single value returned by the subquery with the expression in theWHERE clause.
BROADCAST_SUBQUERY_ERROR schema=xxx process=xxx query_block=xxx message=xxx 小表广播模式查询的子查询失败,请检查SQL,或进一步联系技术支持。 30015 Select localnode by resource, all unavailable= NA 30016 CACHE_QUERY_FAILED message=xxx Cache表查询失败,请检查SQL,或进一步联系技术支持。 30017 COMPUTENODE执...
When used with a subquery, the word IN is an alias for = ANY. Thus, these two statements are the same: SELECT s1 FROM t1 WHERE s1 = ANY (SELECT s1 FROM t2); SELECT s1 FROM t1 WHERE s1 IN (SELECT s1 FROM t2); IN and = ANY are not synonyms when used with an expression list...
A subquery is a SELECT statement within another statement 关于子查询,我有一些自己的理解,select得到的结果其实和table的结构很类似,select查询本身就是在table和select_expr中进行,那么,只要是结果是这两者的,我们都可以使用select去查询,于是就有上面的很多骚操作。