fixes #6792, use a simpler composite in condition implementation

[nineinchnick]

The (a,b) IN ((1,2)) notation is not supported by MySQL/MariaDB and SQLite, only PostgreSQL.

fixes #6792

[qiangxue]

The (a,b) IN ((1,2)) notation is not supported by MySQL/MariaDB

It works well for MySQL 5.1 and above. See http://sqlfiddle.com/#!2/72132/4/0
It doesn't work with SQLite, though.

[nineinchnick]

Right, somehow I didn't find it in the docs before and didn't actually run the query. Should we test other databases before deciding which implementation should be default?

For reference, it's the ROW() expression syntax mentioned on the expressions manual page.

Now it occured to me that maybe a more verbose ROW() form should be used instead of () only, like `ROW(a, b) IN (ROW(1,2)). Should I make a separate PR for this?

[qiangxue]

Yes, we should test other DBMS (sqlfiddle should allow us to try different DBMS, but I didn't have time to try them).

[nineinchnick]

After some research, I've updated the PR and here are my findings.

Only MSSQL and SQLite doesn't support this notation.

References:

• for MSSQL: the manual for in condition and expressions and an article about in condition.
• fro SQLite: the manual for expressions

The composite IN condition for a list of values can be implemented using simple OR/AND operators. There is a problem with subqueries. It is possible, but require aliased column names to be used in the condition. Since I don't think it's possible to extract a valid alias to prepend to column names I added throwing exceptions in that case.

The solution would be to build a EXISTS (SELECT 1 FROM (subquery) a WHERE a.column1 = topQuery.column1 AND a.column2 = topQuery.column2) condition, but there's a problem with the topQuery alias. The EXISTS (subquery) is supported by both MSSQL and SQLite.

[nineinchnick]

This was a bug, making the else part below never to execute. I've removed this cast.

[qiangxue]

Good job!

[qiangxue]

Thank you for your excellent work!

[coveralls]

Changes Unknown when pulling d87f636 on nineinchnick:composite-in-condition-fix-6792 into * on yiisoft:master*.