Support concatenation filter #62

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SijmenSchoon · 2019-10-30T18:21:41Z

SijmenSchoon commented

2019-10-30 18:21:41 +00:00

There currently is no way to concatenate two strings in all supported engines:

RDBMS	Operator	Function
MySQL	`a ∣∣ b`	`CONCAT(a, b)`
PostgreSQL	`a ∣∣ b`	`CONCAT(a, b)`
Oracle	`a ∣∣ b`	`CONCAT(a, b)`
MS SQL	`a + b`	`CONCAT(a, b)`
SQLite	`a ∣∣ b`	-

Thanks to MS SQL and SQLite, there is no common solution. Adding a filter to replace e.g. || with + for MS SQL will fix this problem.

There currently is no way to concatenate two strings in all supported engines: RDBMS | Operator | Function -----------|----------|---------- MySQL | `a ∣∣ b` | `CONCAT(a, b)` PostgreSQL | `a ∣∣ b` | `CONCAT(a, b)` Oracle | `a ∣∣ b` | `CONCAT(a, b)` MS SQL | `a + b` | `CONCAT(a, b)` SQLite | `a ∣∣ b` | - Thanks to MS SQL and SQLite, there is no common solution. Adding a filter to replace e.g. `||` with `+` for MS SQL will fix this problem.

lunny commented

2019-10-31 01:35:34 +00:00

@SijmenSchoon what do you want to use them? Could you give some example?

SijmenSchoon commented

2019-10-31 08:07:51 +00:00

I want to use it for a gitea migration:

_, err := x.Exec("UPDATE `issue` SET `ref` = 'refs/heads/' || `ref`")

This query does not work on MS SQL, because it expects a + for concatenation, and

_, err := x.Exec("UPDATE `issue` SET `ref` = CONCAT('refs/heads/', `ref`)")

does not work for SQLite, since it does not support CONCAT.

I want to use it for a [gitea migration](https://github.com/go-gitea/gitea/pull/8742): ```go _, err := x.Exec("UPDATE `issue` SET `ref` = 'refs/heads/' || `ref`") ``` This query does not work on MS SQL, because it expects a `+` for concatenation, and ```go _, err := x.Exec("UPDATE `issue` SET `ref` = CONCAT('refs/heads/', `ref`)") ``` does not work for SQLite, since it does not support `CONCAT`.

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