add support for joins on delete #89

imle · 2022-08-09T16:06:22Z

imle commented

2022-08-09 16:06:22 +00:00

No description provided.

imle commented

2022-08-09 16:21:05 +00:00

@lunny is the failing build due to something I've done? It looks like the build is not respecting the go.mod go version?

lunny commented

2022-08-09 16:25:34 +00:00

Looks like golang.org/x/tools v0.1.12 now require go 1.18

imle commented

2022-08-09 17:15:54 +00:00

Should I address that in this PR or would you rather it be addressed in a separate PR and I rebase onto that?

lunny reviewed 2022-08-10 03:55:51 +00:00

builder_delete.go Outdated

						
				@ -25,2 +26,3 @@

					return b.cond.WriteTo(w)

					if len(b.joins) > 0 {

						parts := strings.Split(b.from, " ")

lunny commented

2022-08-10 03:55:51 +00:00

b.from?

imle commented

2022-08-10 04:38:18 +00:00

The goal here is when one or more joins are specified, we want to get the table alias or name for the following syntax:

DELETE t1 FROM table1 t1 LEFT JOIN t2 ON t1.id = t2.id WHERE t2.id IS NULL;
DELETE table1 FROM table1 LEFT JOIN t2 ON table1.id = t2.id WHERE t2.id IS NULL;

It is required to specify the table you want the deletes to occur in when referencing multiple tables.
https://dev.mysql.com/doc/refman/8.0/en/delete.html

In this line of code, I am getting the last part of the b.from (which is the table name or its alias) and specifying to use it for deletes.

This approach means there is no way to specify that you want to delete from t1 and t2, but short of changing the Delete() definition and behavior, I don't see a great way to do so.

The goal here is when one or more joins are specified, we want to get the table alias or name for the following syntax: ``` DELETE t1 FROM table1 t1 LEFT JOIN t2 ON t1.id = t2.id WHERE t2.id IS NULL; DELETE table1 FROM table1 LEFT JOIN t2 ON table1.id = t2.id WHERE t2.id IS NULL; ``` It is required to specify the table you want the deletes to occur in when referencing multiple tables. https://dev.mysql.com/doc/refman/8.0/en/delete.html In this line of code, I am getting the last part of the `b.from` (which is the table name or its alias) and specifying to use it for deletes. This approach means there is no way to specify that you want to delete from `t1` and `t2`, but short of changing the `Delete()` definition and behavior, I don't see a great way to do so.

lunny commented

2022-08-10 05:29:49 +00:00

Is this a standard SQL syntax? Where could I find some related articles?

imle commented

2022-08-10 06:45:54 +00:00

It seems to be supported in MySQL, MSSQL.
https://www.educba.com/sql-delete-join/

However, it does not seem to be supported in Postgres, SQLite, or Oracle.

It seems to be supported in MySQL, MSSQL. https://www.educba.com/sql-delete-join/ However, it does not seem to be supported in Postgres, SQLite, or Oracle.