根据条件从2个不同的表中选择数据; MySQL的

时间:2022-03-01 14:15:11

I have 2 tables; table A and table B

我有2张桌子;表A和表B.

Table A has 3 columns; a, b, c Table B has 2 columns; d and e

表A有3列; a,b,c表B有2列; d和e

I want to select IF A.b is NOT NULL THEN SELECT A.b ELSE IF A.b IS NULL THEN SELECT B.d

我想选择IF A.b是非NULL然后选择A.b ELSE如果A.b IS NULL那么SELECT B.d

any help please

请帮忙

I just made up this example, but if required then say A.a and A.c are unique ids.

我刚刚编写了这个例子,但如果需要,那么说A.a和A.c是唯一的ID。

1 个解决方案

#1


0  

Give it a try!

试试看!

// select data from your database

//从数据库中选择数据

Select * From TABLE_A

选择*来自TABLE_A

if((A.a != "") || (A.a != NULL)){

 // select d from table B


} else {

// echo records from your column B 

}

#1


0  

Give it a try!

试试看!

// select data from your database

//从数据库中选择数据

Select * From TABLE_A

选择*来自TABLE_A

if((A.a != "") || (A.a != NULL)){

 // select d from table B


} else {

// echo records from your column B 

}