Function NewDMLUpdateQueryBuilder

go/sql/builder.go:921–966

NewDMLUpdateQueryBuilder creates a new DMLUpdateQueryBuilder. It prepares the UPDATE query statement. Returns an error if no shared columns are given, the shared columns are not a subset of the table columns, no unique key columns are given or the prepared statement cannot be built.

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

// Returns an error if no shared columns are given, the shared columns are not a subset of the table columns,
// no unique key columns are given or the prepared statement cannot be built.
func NewDMLUpdateQueryBuilder(databaseName, tableName string, tableColumns, sharedColumns, mappedSharedColumns, uniqueKeyColumns *ColumnList) (*DMLUpdateQueryBuilder, error) {
	if !sharedColumns.IsSubsetOf(tableColumns) {
		return nil, fmt.Errorf("shared columns is not a subset of table columns in NewDMLUpdateQueryBuilder")
	}
	if sharedColumns.Len() == 0 {
		return nil, fmt.Errorf("no shared columns found in NewDMLUpdateQueryBuilder")
	}
	if uniqueKeyColumns.Len() == 0 {
		return nil, fmt.Errorf("no unique key columns found in NewDMLUpdateQueryBuilder")
	}
	// If unique key contains virtual columns, those column won't be in sharedColumns
	// which only contains non-virtual columns
	nonVirtualUniqueKeyColumns := uniqueKeyColumns.FilterBy(func(column Column) bool { return !column.IsVirtual })
	if !nonVirtualUniqueKeyColumns.IsSubsetOf(sharedColumns) {
		return nil, fmt.Errorf("unique key columns is not a subset of shared columns in NewDMLUpdateQueryBuilder")
	}
	databaseName = EscapeName(databaseName)
	tableName = EscapeName(tableName)
	setClause, err := BuildSetPreparedClause(mappedSharedColumns)
	if err != nil {
		return nil, err
	}

	equalsComparison, err := BuildEqualsPreparedComparison(uniqueKeyColumns.Names())
	if err != nil {
		return nil, err
	}
	stmt := fmt.Sprintf(`
		update /* gh-ost %s.%s */
			%s.%s
		set
			%s
		where
			%s`,
		databaseName, tableName,
		databaseName, tableName,
		setClause,
		equalsComparison,
	)
	return &DMLUpdateQueryBuilder{
		tableColumns:      tableColumns,
		sharedColumns:     sharedColumns,
		uniqueKeyColumns:  uniqueKeyColumns,
		preparedStatement: stmt,
	}, nil
}

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