ErrExpressionTooLong: {
		Code:           "ExpressionTooLong",
		Description:    "The SQL expression is too long: The maximum byte-length for the SQL expression is 256 KB.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrIllegalSQLFunctionArgument: {
		Code:           "IllegalSqlFunctionArgument",
		Description:    "Illegal argument was used in the SQL function.",
		HTTPStatusCode: http.StatusBadRequest,
	},
	ErrInvalidKeyPath: {

//		 return c.db.BeginTx(ctx, opts)
//	}
//
// You should use BeginTx returned gorm.Tx which could wrap *sql.Tx then you can record all queries.
func (c *wrapperConnPool) BeginTx(ctx context.Context, opts *sql.TxOptions) (gorm.ConnPool, error) {
	tx, err := c.db.BeginTx(ctx, opts)
	if err != nil {
		return nil, err
	}
	return &wrapperTx{Tx: tx, conn: c}, nil
}

```

一般是在 `main.py` 中调用这行代码，但在 `main.py` 里，这行代码用于创建 `sql_app.db`，但是现在要为测试创建 `test.db`。

因此，要在测试代码中添加这行代码创建新的数据库文件。

```Python hl_lines="16"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

## 覆盖依赖项

接下来，创建覆盖依赖项，并为应用添加覆盖内容。

```Python hl_lines="19-24  27"
{!../../../docs_src/sql_databases/sql_app/tests/test_sql_app.py!}
```

!!! tip "提示"

		db.AddError(ErrUnsupportedDriver)
	}
	return db
}

// Exec executes raw sql
func (db *DB) Exec(sql string, values ...interface{}) (tx *DB) {
	tx = db.getInstance()
	tx.Statement.SQL = strings.Builder{}

	if strings.Contains(sql, "@") {
		clause.NamedExpr{SQL: sql, Vars: values}.Build(tx.Statement)
	} else {
		clause.Expr{SQL: sql, Vars: values}.Build(tx.Statement)
	}

	return tx.callbacks.Raw().Execute(tx)

					v.Dialector.BindVarTo(&bindvar, subdb.Statement, vv)
					sql = strings.Replace(sql, bindvar.String(), "?", 1)
				}

				subdb.Statement.SQL.Reset()
				subdb.Statement.Vars = stmt.Vars
				if strings.Contains(sql, "@") {
					clause.NamedExpr{SQL: sql, Vars: vars}.Build(subdb.Statement)
				} else {
					clause.Expr{SQL: sql, Vars: vars}.Build(subdb.Statement)
				}
			} else {

            return (java.sql.Date) src;
        }
        if (src instanceof Date) {
            return new java.sql.Date(((Date) src).getTime());
        }
        if (src instanceof Calendar) {
            return new java.sql.Date(((Calendar) src).getTimeInMillis());
        }
        final String str = src.toString();
        if (isEmpty(str)) {
            return null;
        }

		}
	case *int, *int8, *int16, *int32, *int64,
		*uint, *uint8, *uint16, *uint32, *uint64, *uintptr,
		*float32, *float64,
		*bool, *string, *time.Time,
		*sql.NullInt32, *sql.NullInt64, *sql.NullFloat64,
		*sql.NullBool, *sql.NullString, *sql.NullTime:
		for initialized || rows.Next() {
			initialized = false
			db.RowsAffected++
			db.AddError(rows.Scan(dest))
		}
	default:
		var (

package gorm

import (
	"context"
	"database/sql"
	"database/sql/driver"
	"errors"
	"reflect"
	"sync"
)

type Stmt struct {
	*sql.Stmt
	Transaction bool
	prepared    chan struct{}
	prepareErr  error
}

type PreparedStmtDB struct {
	Stmts       map[string]*Stmt
	PreparedSQL []string
	Mux         *sync.RWMutex
	ConnPool
}

func NewPreparedStmtDB(connPool ConnPool) *PreparedStmtDB {

					if e, ok := v.Exprs[0].(Expr); ok {
						sql := strings.ToUpper(e.SQL)
						wrapInParentheses = strings.Contains(sql, AndWithSpace) || strings.Contains(sql, OrWithSpace)
					}
				}
			case AndConditions:
				if len(v.Exprs) == 1 {
					if e, ok := v.Exprs[0].(Expr); ok {
						sql := strings.ToUpper(e.SQL)
						wrapInParentheses = strings.Contains(sql, AndWithSpace) || strings.Contains(sql, OrWithSpace)
					}
				}
			case Expr:

		return gorm.ErrSubQueryRequired
	}

	sql := new(strings.Builder)
	sql.WriteString("CREATE ")
	if option.Replace {
		sql.WriteString("OR REPLACE ")
	}
	sql.WriteString("VIEW ")
	m.QuoteTo(sql, name)
	sql.WriteString(" AS ")

	m.DB.Statement.AddVar(sql, option.Query)

	if option.CheckOption != "" {
		sql.WriteString(" ")
		sql.WriteString(option.CheckOption)
	}