gorm/dialect.go

51 lines
1.6 KiB
Go

package gorm
import (
"fmt"
"reflect"
)
// Dialect interface contains behaviors that differ across SQL database
type Dialect interface {
// BindVar return the placeholder for actual values in SQL statements, in many dbs it is "?", Postgres using $1
BindVar(i int) string
// Quote quotes field name to avoid SQL parsing exceptions by using a reserved word as a field name
Quote(key string) string
// DataTypeOf return data's sql type
DataTypeOf(value reflect.Value, tagSettings map[string]string) string
// HasIndex check has index or not
HasIndex(scope *Scope, tableName string, indexName string) bool
// RemoveIndex remove index
RemoveIndex(scope *Scope, indexName string)
// HasTable check has table or not
HasTable(scope *Scope, tableName string) bool
// HasColumn check has column or not
HasColumn(scope *Scope, tableName string, columnName string) bool
// LimitAndOffsetSQL return generate SQL with limit and offset, as mssql has special case
LimitAndOffsetSQL(limit, offset int) string
// SelectFromDummyTable return select values, for most dbs, `SELECT values` just works, mysql needs `SELECT value FROM DUAL`
SelectFromDummyTable() string
// LastInsertIdReturningSuffix most dbs support LastInsertId, but postgres needs to use `RETURNING`
LastInsertIdReturningSuffix(tableName, columnName string) string
}
func NewDialect(driver string) Dialect {
var d Dialect
switch driver {
case "postgres":
d = &postgres{}
case "mysql":
d = &mysql{}
case "sqlite3":
d = &sqlite3{}
case "mssql":
d = &mssql{}
default:
fmt.Printf("`%v` is not officially supported, running under compatibility mode.\n", driver)
d = &commonDialect{}
}
return d
}