问题
I am trying to compare number of rows of two tables in two databases. The number of rows should be the same :
SELECT
(SELECT COUNT(*) FROM db1.table1)-
(SELECT COUNT(*) FROM db2.table1) AS difference
How do i select only if difference<>0? I need to run this for multiple tables and i don't need 0 values. I could load results in C# list and sort it out but i'd like to finish all in query.
I've tried using information_schema.TABLES for this but it's not suitable because it returns approximate results. I'm using Mysql 5.5
回答1:
SELECT * FROM (SELECT (SELECT COUNT() FROM db1.table1) - (SELECT COUNT() FROM db2.table1) AS t, "table1"AS table) X WHERE x.t1<>0 UNION ALL SELECT * FROM (SELECT (SELECT COUNT() FROM db1.table2) - (SELECT COUNT() FROM db2.table2) AS t, "table2"AS table) X WHERE x.t<>0
来源：https://stackoverflow.com/questions/45368388/mysql-select-difference-of-rows-counts-in-two-tables