How to Identify \'Database Does Not Exist\' Errors with the Postgres Driver?

Determining the Code of an Error Returned by db.Exec(...)

In the process of deleting a database using the Postgres driver (lib/pq), an attempt is made to differentiate between ordinary errors and "database does not exist" errors. To accomplish this, the following question arises:

Is there a constant variable or mechanism that can be used to identify whether the returned error indicates that the database does not exist, or is manual parsing of the error string necessary?

While the Postgres documentation lacks specific mention of "database does not exist" error codes, the lib/pq package returns errors of type *pq.Error, a struct with various fields providing detailed error information.

To check for error codes and perform the desired conditional action, proceed as follows:

<code class="go">if err, ok := err.(*pq.Error); ok {
  // Here err is of type *pq.Error, you may inspect all its fields, e.g.:
  fmt.Println("pq error:", err.Code.Name())
}</code>

The *pq.Error struct includes the following fields, each containing Postres-specific information and values:

<code class="go">type Error struct {
    Severity         string
    Code             ErrorCode
    Message          string
    Detail           string
    Hint             string
    Position         string
    InternalPosition string
    InternalQuery    string
    Where            string
    Schema           string
    Table            string
    Column           string
    DataTypeName     string
    Constraint       string
    File             string
    Line             string
    Routine          string
}</code>

The full list of meanings and possible values for these fields can be found in the Postgres documentation at: Error and Notice Message Fields.

By utilizing these fields, it is possible to precisely identify and handle the desired error conditions when using the Postgres driver for database operations.

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