Function GetCharsetAndDefaultCollation

dumpling/export/sql.go:1614–1654

GetCharsetAndDefaultCollation gets charset and default collation map.

(ctx context.Context, db *sql.Conn)

// GetCharsetAndDefaultCollation gets charset and default collation map.
func GetCharsetAndDefaultCollation(ctx context.Context, db *sql.Conn) (map[string]string, error) {
	charsetAndDefaultCollation := make(map[string]string)
	query := "SHOW CHARACTER SET"

	// Show an example.
	/*
		mysql> SHOW CHARACTER SET;
		+----------+---------------------------------+---------------------+--------+
		| Charset  | Description                     | Default collation   | Maxlen |
		+----------+---------------------------------+---------------------+--------+
		| armscii8 | ARMSCII-8 Armenian              | armscii8_general_ci |      1 |
		| ascii    | US ASCII                        | ascii_general_ci    |      1 |
		| big5     | Big5 Traditional Chinese        | big5_chinese_ci     |      2 |
		| binary   | Binary pseudo charset           | binary              |      1 |
		| cp1250   | Windows Central European        | cp1250_general_ci   |      1 |
		| cp1251   | Windows Cyrillic                | cp1251_general_ci   |      1 |
		+----------+---------------------------------+---------------------+--------+
	*/

	rows, err := db.QueryContext(ctx, query)
	if err != nil {
		return nil, errors.Annotatef(err, "sql: %s", query)
	}

	defer rows.Close()
	for rows.Next() {
		var charset, description, collation string
		var maxlen int
		if scanErr := rows.Scan(&charset, &description, &collation, &maxlen); scanErr != nil {
			return nil, errors.Annotatef(err, "sql: %s", query)
		}
		charsetAndDefaultCollation[strings.ToLower(charset)] = collation
	}
	if err = rows.Close(); err != nil {
		return nil, errors.Annotatef(err, "sql: %s", query)
	}
	if err = rows.Err(); err != nil {
		return nil, errors.Annotatef(err, "sql: %s", query)
	}
	return charsetAndDefaultCollation, err
}