sql查询以根据组合条件返回数据

Question

Need to code a sql to filter records form a table based on combination conditions. show records if column_1 is "A" and then column_2 is "100" OR if column_1 is "B" and then column_2 is "200"

    select * 
    from tableTmp
    where 
name="student"
and ((column_1="A" and column_2 = "100") OR (column_1="B" and column_2 = "200"))

when the first condition is not there, it will show what we want. but if there is first condition, then column_1="C" data still will show, the query is broken.

do you know why ?

Answer 1

Use single quotes for literals:

select * 
from tableTmp
where name='student'
and (
    (column_1='A' and column_2 = '100') 
 OR (column_1='B' and column_2 = '200')
 )

However I cannot see how a column_1 value of 'C' can be returned by that query.

Nb. If column_2 is a numeric data type don't use single quotes.