使用 If else 条件选择 mysql 中的列？
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use the If else condition for selecting the column in mysql?
提问by svk
I am having two tables like this.Both are separate tables
我有两张这样的桌子。都是单独的桌子
AccountNo User Name
----------------------------------
1 U a
2 U b
3 U c
And another table contains the following structure
另一个表包含以下结构
TempAccountNo Mycolumn AccountNo
------------------------------------------
4 X 2341
5 Y 2
6 Z 2568
I need to select the AccountNo or TempAccountNo,Mycolumn From table II and the condition is
我需要从表 II 中选择 AccountNo 或 TempAccountNo,Mycolumn 并且条件是
If (tableII.AccountNo not in table I)
I need to choose TempAccountNo from table II
我需要选择 TempAccountNo from table II
else
I need to choose AccountNo from table II
我需要选择 AccountNo from table II
How can I achieve this.
我怎样才能做到这一点。
回答by zerkms
SELECT IF(t1.AccountNo IS NULL, t2.TempAccountNo, t2.AccountNo) AS optional_field
FROM table2 t2
LEFT JOIN t1 ON t1.AccountNo = t2.AccountNo
回答by Er. Nilesh G. Pangul
I have a mysql query for multiple select field using if ... else statements or using case statement. This is described below.
我使用 if ... else 语句或 using case 语句对多个选择字段进行了 mysql 查询。这在下面描述。
MYSQL select using if statement
select IF('fieldname with condition','if true value','if false value') from table_name where 1;MYSQL select using multiple if else
select CASE WHEN fieldname1 = 'value1' THEN 'if true then give value' WHEN fieldname2 = 'value2' THEN 'if true then give value' THEN 'if true then give value' WHEN fieldname3 = 'value3' THEN 'if true then give value' THEN 'if true then give value' WHEN fieldname4 = 'value4' THEN 'if true then give value' THEN 'if true then give value' ELSE 'else all false then give default value' END as STATUS, from table_name where 1;
MYSQL 选择使用 if 语句
select IF('fieldname with condition','if true value','if false value') from table_name where 1;MYSQL选择使用多个if else
select CASE WHEN fieldname1 = 'value1' THEN 'if true then give value' WHEN fieldname2 = 'value2' THEN 'if true then give value' THEN 'if true then give value' WHEN fieldname3 = 'value3' THEN 'if true then give value' THEN 'if true then give value' WHEN fieldname4 = 'value4' THEN 'if true then give value' THEN 'if true then give value' ELSE 'else all false then give default value' END as STATUS, from table_name where 1;
Try using these queries.
尝试使用这些查询。
回答by Prabhagaran
SELECT IF(t1.AccountNo IS NULL, t2.TempAccountNo, t2.AccountNo) AS Acc_common
FROM table1 t1
INNER JOIN table2 t2 ON t1.AccountNo = t2.AccountNo
This will help..
这将有助于..
