在Go中处理动态错误（特别是数据库/ sql程序包）

Question

Using the database/sql package in go for things like sql.Exec will return dynamically generated, unreferenced errors such as

"Error 1062: Duplicate entry '192' for key 'id'"

The problem is that it can also return errors such as

"Error 1146: Table 'tbl' doesn't exist"

From the same call to sql.Exec

How can I tell the difference between these two errors without

1. String comparison, or
2. Pattern matching for error code

Or are those idiomatic viable solutions for this problem?

Answer 1

database/sql package does not solve this problem. It's driver specific. For example, for mysql you can use:

if mysqlError, ok := err.(*mysql.MySQLError); ok {
    if mysqlError.Number == 1146 {
        //handling
    }
}

Also, you can find some error constant package, like mysqlerr from VividCortex, and use it:

if mysqlError, ok := err.(*mysql.MySQLError); ok {
    if mysqlError.Number == mysqlerr.ER_NO_SUCH_TABLE {
        //handling
    }
}

It's not much better than pattern matching, but seems to be more idiomatic.