Function NewDMLDeleteQueryBuilder

go/sql/builder.go:802–830

NewDMLDeleteQueryBuilder creates a new DMLDeleteQueryBuilder. It prepares the DELETE query statement. Returns an error if no unique key columns are given or the prepared statement cannot be built.

(databaseName, tableName string, tableColumns, uniqueKeyColumns *ColumnList)

// Returns an error if no unique key columns are given
// or the prepared statement cannot be built.
func NewDMLDeleteQueryBuilder(databaseName, tableName string, tableColumns, uniqueKeyColumns *ColumnList) (*DMLDeleteQueryBuilder, error) {
	if uniqueKeyColumns.Len() == 0 {
		return nil, fmt.Errorf("no unique key columns found in NewDMLDeleteQueryBuilder")
	}
	databaseName = EscapeName(databaseName)
	tableName = EscapeName(tableName)
	equalsComparison, err := BuildEqualsPreparedComparison(uniqueKeyColumns.Names())
	if err != nil {
		return nil, err
	}

	stmt := fmt.Sprintf(`
		delete /* gh-ost %s.%s */
		from
			%s.%s
		where
			%s`,
		databaseName, tableName,
		databaseName, tableName,
		equalsComparison,
	)

	b := &DMLDeleteQueryBuilder{
		tableColumns:      tableColumns,
		uniqueKeyColumns:  uniqueKeyColumns,
		preparedStatement: stmt,
	}
	return b, nil
}

// BuildQuery builds the arguments array for a DML event DELETE query.
// It returns the query string and the unique key arguments array.