func()

in pkg/datasource/sql/undo/builder/mysql_multi_delete_undo_log_builder.go [109:190]

• 68 lines of code
• 9 McCabe index (conditional complexity)

func (u *MySQLMultiDeleteUndoLogBuilder) buildBeforeImageSQL(multiQuery []string, args []driver.Value) ([]string, []driver.Value, error) {
	var (
		err        error
		buf, param bytes.Buffer
		p          *types.ParseContext
		tableName  string
		tables     = make(map[string]multiDelete, len(multiQuery))
	)

	for _, query := range multiQuery {
		p, err = parser.DoParser(query)
		if err != nil {
			return nil, nil, err
		}

		tableName = p.DeleteStmt.TableRefs.TableRefs.Left.(*ast.TableSource).Source.(*ast.TableName).Name.O

		v, ok := tables[tableName]
		if ok && v.clear {
			continue
		}

		buf.WriteString("delete from ")
		buf.WriteString(tableName)

		if p.DeleteStmt.Where == nil {
			tables[tableName] = multiDelete{sql: buf.String(), clear: true}
			buf.Reset()
			continue
		} else {
			buf.WriteString(" where ")
		}

		_ = p.DeleteStmt.Where.Restore(format.NewRestoreCtx(format.RestoreKeyWordUppercase, &param))

		v, ok = tables[tableName]
		if ok {
			buf.Reset()
			buf.WriteString(v.sql)
			buf.WriteString(" or ")
		}

		buf.Write(param.Bytes())
		tables[tableName] = multiDelete{sql: buf.String()}

		buf.Reset()
		param.Reset()
	}

	var (
		items   = make([]string, 0, len(tables))
		values  = make([]driver.Value, 0, len(tables))
		selStmt = ast.SelectStmt{
			SelectStmtOpts: &ast.SelectStmtOpts{},
			From:           p.DeleteStmt.TableRefs,
			Where:          p.DeleteStmt.Where,
			Fields:         &ast.FieldList{Fields: []*ast.SelectField{{WildCard: &ast.WildCardField{}}}},
			OrderBy:        p.DeleteStmt.Order,
			Limit:          p.DeleteStmt.Limit,
			TableHints:     p.DeleteStmt.TableHints,
			LockInfo:       &ast.SelectLockInfo{LockType: ast.SelectLockForUpdate},
		}
	)

	for _, table := range tables {
		p, _ = parser.DoParser(table.sql)

		selStmt.From = p.DeleteStmt.TableRefs
		selStmt.Where = p.DeleteStmt.Where

		_ = selStmt.Restore(format.NewRestoreCtx(format.RestoreKeyWordUppercase, &buf))
		items = append(items, buf.String())
		buf.Reset()
		if table.clear {
			values = append(values, u.buildSelectArgs(&selStmt, nil)...)
		} else {
			values = append(values, u.buildSelectArgs(&selStmt, args)...)
		}
	}

	return items, values, nil
}