Method Execute

statement.go:710–754

(ctx context.Context, session *Session)

}

func (s *ShowColumnsStatement) Execute(ctx context.Context, session *Session) (*Result, error) {
	if session.InReadWriteTransaction() {
		// INFORMATION_SCHEMA can not be used in read-write transaction.
		// https://cloud.google.com/spanner/docs/information-schema
		return nil, errors.New(`"SHOW COLUMNS" can not be used in a read-write transaction`)
	}

	stmt := spanner.Statement{SQL: `SELECT
  C.COLUMN_NAME as Field,
  C.SPANNER_TYPE as Type,
  C.IS_NULLABLE as ` + "`NULL`" + `,
  I.INDEX_TYPE as Key,
  IC.COLUMN_ORDERING as Key_Order,
  CONCAT(CO.OPTION_NAME, "=", CO.OPTION_VALUE) as Options
FROM
  INFORMATION_SCHEMA.COLUMNS C
LEFT JOIN
  INFORMATION_SCHEMA.INDEX_COLUMNS IC USING(TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME)
LEFT JOIN
  INFORMATION_SCHEMA.INDEXES I USING(TABLE_SCHEMA, TABLE_NAME, INDEX_NAME)
LEFT JOIN
  INFORMATION_SCHEMA.COLUMN_OPTIONS CO USING(TABLE_SCHEMA, TABLE_NAME, COLUMN_NAME)
WHERE
  LOWER(C.TABLE_SCHEMA) = LOWER(@table_schema) AND LOWER(C.TABLE_NAME) = LOWER(@table_name)
ORDER BY
  C.ORDINAL_POSITION ASC`,
		Params: map[string]interface{}{"table_name": s.Table, "table_schema": s.Schema}}

	iter, _ := session.RunQuery(ctx, stmt)
	defer iter.Stop()

	rows, columnNames, err := parseQueryResult(iter)
	if err != nil {
		return nil, err
	}
	if len(rows) == 0 {
		return nil, fmt.Errorf("table %q doesn't exist in schema %q", s.Table, s.Schema)
	}

	return &Result{
		ColumnNames:  columnNames,
		Rows:         rows,
		AffectedRows: len(rows),
	}, nil
}

func extractSchemaAndTable(s string) (string, string) {
	schema, table, found := strings.Cut(s, ".")