SQL sever怎么在以下命令增加一个判断条件？

Question

UPDATE dbo.table1
    SET B.value1= B.value1-A.value2
    FROM dbo.table1 B,dbo.table2 A
    where  B.value3=A.value3

我想加一个判断条件当 B.value1>A.value2的时候才执行以上条件，怎么加？

Answer 1

UPDATE dbo.table1 SET B.value1= B.value1-A.value2 FROM dbo.table1 B,dbo.table2 A
where B.value3=A.value3 and B.valuue1 > A.value2