Simple and Powerful ORM for Go, support mysql,postgres,tidb,sqlite3,mssql,oracle https://xorm.io
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  1. // Copyright 2017 The Xorm Authors. All rights reserved.
  2. // Use of this source code is governed by a BSD-style
  3. // license that can be found in the LICENSE file.
  4. package xorm
  5. import (
  6. "errors"
  7. "fmt"
  8. "reflect"
  9. "xorm.io/builder"
  10. "xorm.io/core"
  11. )
  12. // Exist returns true if the record exist otherwise return false
  13. func (session *Session) Exist(bean ...interface{}) (bool, error) {
  14. if session.isAutoClose {
  15. defer session.Close()
  16. }
  17. if session.statement.lastError != nil {
  18. return false, session.statement.lastError
  19. }
  20. var sqlStr string
  21. var args []interface{}
  22. var err error
  23. if session.statement.RawSQL == "" {
  24. if len(bean) == 0 {
  25. tableName := session.statement.TableName()
  26. if len(tableName) <= 0 {
  27. return false, ErrTableNotFound
  28. }
  29. tableName = session.statement.Engine.Quote(tableName)
  30. if session.statement.cond.IsValid() {
  31. condSQL, condArgs, err := builder.ToSQL(session.statement.cond)
  32. if err != nil {
  33. return false, err
  34. }
  35. if session.engine.dialect.DBType() == core.MSSQL {
  36. sqlStr = fmt.Sprintf("SELECT TOP 1 * FROM %s WHERE %s", tableName, condSQL)
  37. } else if session.engine.dialect.DBType() == core.ORACLE {
  38. sqlStr = fmt.Sprintf("SELECT * FROM %s WHERE (%s) AND ROWNUM=1", tableName, condSQL)
  39. } else {
  40. sqlStr = fmt.Sprintf("SELECT * FROM %s WHERE %s LIMIT 1", tableName, condSQL)
  41. }
  42. args = condArgs
  43. } else {
  44. if session.engine.dialect.DBType() == core.MSSQL {
  45. sqlStr = fmt.Sprintf("SELECT TOP 1 * FROM %s", tableName)
  46. } else if session.engine.dialect.DBType() == core.ORACLE {
  47. sqlStr = fmt.Sprintf("SELECT * FROM %s WHERE ROWNUM=1", tableName)
  48. } else {
  49. sqlStr = fmt.Sprintf("SELECT * FROM %s LIMIT 1", tableName)
  50. }
  51. args = []interface{}{}
  52. }
  53. } else {
  54. beanValue := reflect.ValueOf(bean[0])
  55. if beanValue.Kind() != reflect.Ptr {
  56. return false, errors.New("needs a pointer")
  57. }
  58. if beanValue.Elem().Kind() == reflect.Struct {
  59. if err := session.statement.setRefBean(bean[0]); err != nil {
  60. return false, err
  61. }
  62. }
  63. if len(session.statement.TableName()) <= 0 {
  64. return false, ErrTableNotFound
  65. }
  66. session.statement.Limit(1)
  67. sqlStr, args, err = session.statement.genGetSQL(bean[0])
  68. if err != nil {
  69. return false, err
  70. }
  71. }
  72. } else {
  73. sqlStr = session.statement.RawSQL
  74. args = session.statement.RawParams
  75. }
  76. rows, err := session.queryRows(sqlStr, args...)
  77. if err != nil {
  78. return false, err
  79. }
  80. defer rows.Close()
  81. return rows.Next(), nil
  82. }