sql - 用多个条件更新多行“每一行都有不同的条件”

Question

我想创建一个更新 sql 语句，该语句可以更新具有多个条件的多行，每行取决于不同的条件，例如：

UPDATE tableName
SET row1_field1=newValue1, Row1_field2=newValue2 
WHERE row1_condition1=condition1
  AND SET row2_field1=newValue1, row2_field2=newValue2 WHERE row2_condition1=condition1
  AND SET row3_field1=newValue1, row3_field2=newValue2 WHERE row3_condition1=condition1

Answer 1

Try something like this

UPDATE tableName
SET row1_field1=case when row1_condition1=condition1 then newValue1 end, 
Row1_field2=case when row1_condition1=condition1 then newValue2 end,
row2_field1=case when row2_condition1=condition1 then newValue1 end , 
etc

Answer 2

为此，您应该使用CASE UPDATE。网上有很多例子。

例如：

update table set
    columnx = (case when condition then new_valuex else columnx end),
    columny = (case when condition then new_valuey else columny end)

Answer 3

你不能这么简单地动态地做到这一点。您必须<conditionRow..>在 WHEN 子句中输入硬编码值：

UPDATE tableName
SET field1 = CASE WHEN condition = <conditionRow1_field1> THEN newValue1 
                  WHEN condition = <conditionRow2_field1> THEN newValue2 
                  ...
             ELSE field1 END,
    field1 = CASE WHEN condition = <conditionRow1_field2> THEN newValueRow1_field2 
                  WHEN condition = <conditionRow2_field1> THEN newValueRow2_field2 
                  ...
             ELSE field2 END