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; ...
SQL:搞懂case语句,看这篇就可以啦! SQL里CASE 语句允许数分同学在查询中执行条件逻辑。了解如何使用其功能可以显著增强工作效率和数据处理的能力。在本文中,我们将深入探讨 SQL CASE 语句,涵盖其语法、各种用例,并提供实用的代码示例来巩固大家的理解。 Part1-了解 SQL CASE 语句 CASE 语句提供了在 SQL 查询中执行...
CASE in select queryPosted by: jim giner Date: April 04, 2012 02:31PM I vaguely remember using a case clause in a select statement in a former occupation, but now that I am using mysql (with php) I am encountering my first need for it and don't know if I can do what I want...
CASE WHEN col_1 IN ( 'a', 'b') THEN '第一类' WHEN col_1 IN ('a') THEN '第二类' ELSE'其他' END === update ffmpeg_agent_node set remark = case when isnull(remark) then 'docker' else concat(remark, '123') end where name = '10.77.40.194'; mysql> select * from ffmpeg_cmd...
mysql> call exp_case(1); Query OK,1row affected (0.09sec) mysql> call exp_case(2); Query OK,1row affected (0.03sec) mysql>select*fromstudentswheresidin(1,2);+---+---+---+---+---+ | sid | sname | gender | dept_id | brithday | +...
root@mysqldb 13:03: [test]> create table T1(id int); Query OK, 0 rows affected (0.08 sec) root@mysqldb 13:03: [test]> show tables; +---+ | Tables_in_test | +---+ | T1 | | t1 | | t2 | +---+ 3 rows in set (0.00 sec) root@mysqldb 13:03: [test]> select * from...
示例:在查询中使用简单的 CASE 表达式,将国家代码缩写翻译为全称。 obclient>CREATETABLEt_case(id numberNOTNULLPRIMARYKEY,abbrvarchar(5));QueryOK,0rowsaffected(0.08sec)obclient>INSERTINTOt_case(id,abbr)VALUES(1,'US'),(2,'UK'),(3,'CN'),(4,'JP');QueryOK,4rowsaffected(0.02sec)Records:4Dup...
设置用户自定义变量 -- 语法1,使用 = set @myname = 'zjj'; set @myage = 20; -- 语法2,使用 := set @mygender := '男',@myhobby := 'java'; mysql> set @myname = 'zjj';set @myage = 20;set @mygender := '男',@myhobby := 'java'; Query OK, 0 rows ...
mysql> SET @QQ=CONCAT('SELECT ifnull(c1,\'total\'),',LEFT(@EE,LENGTH(@EE)-1),' ,SUM(C3) AS TOTAL FROM TX GROUP BY C1 WITH ROLLUP'); Query OK, 0 rows affected (0.00 sec) mysql> PREPARE stmt2 FROM @QQ; Query OK, 0 rows affected (0.00 sec) ...
I've a case in my query, and what i want is use the result from this case in where. Here my case: CASE WHEN rtadates_tbl.rta IS NOT NULL THEN DATE_FORMAT(rtadates_tbl.rta, "%d.%m.%Y") WHEN rtadates.rta IS NOT NULL