sql

package
v0.0.0-...-1d03baa Latest Latest
Warning

This package is not in the latest version of its module.

 Go to latest Published: Jan 21, 2013 License: BSD-3-Clause Imports: 7 Imported by: 0

Documentation

Overview

Package sql provides a generic interface around SQL (or SQL-like) databases.

Index

Examples

Constants

This section is empty.

Variables

View Source 
var ErrNoRows = errors.New("sql: no rows in result set")

ErrNoRows is returned by Scan when QueryRow doesn't return a row. In such a case, QueryRow returns a placeholder *Row value that defers this error until a Scan.

View Source 
var ErrTxDone = errors.New("sql: Transaction has already been committed or rolled back")

Functions

func Register 

func Register(name string, driver driver.Driver)

Register makes a database driver available by the provided name. If Register is called twice with the same name or if driver is nil, it panics.

Types

type DB 

type DB struct {
	// contains filtered or unexported fields
}

DB is a database handle. It's safe for concurrent use by multiple goroutines.

If the underlying database driver has the concept of a connection and per-connection session state, the sql package manages creating and freeing connections automatically, including maintaining a free pool of idle connections. If observing session state is required, either do not share a *DB between multiple concurrent goroutines or create and observe all state only within a transaction. Once DB.Open is called, the returned Tx is bound to a single isolated connection. Once Tx.Commit or Tx.Rollback is called, that connection is returned to DB's idle connection pool.

func Open 

func Open(driverName, dataSourceName string) (*DB, error)

Open opens a database specified by its database driver name and a driver-specific data source name, usually consisting of at least a database name and connection information.

Most users will open a database via a driver-specific connection helper function that returns a *DB.

func (*DB) Begin 

func (db *DB) Begin() (*Tx, error)

Begin starts a transaction. The isolation level is dependent on the driver.

func (*DB) Close 

func (db *DB) Close() error

Close closes the database, releasing any open resources.

func (*DB) Driver 

func (db *DB) Driver() driver.Driver

Driver returns the database's underlying driver.

func (*DB) Exec 

func (db *DB) Exec(query string, args ...interface{}) (Result, error)

Exec executes a query without returning any rows.

func (*DB) Prepare 

func (db *DB) Prepare(query string) (*Stmt, error)

Prepare creates a prepared statement for later execution.

func (*DB) Query 

func (db *DB) Query(query string, args ...interface{}) (*Rows, error)

Query executes a query that returns rows, typically a SELECT. The args are for any placeholder parameters in the query.

Example 
package main

import (
	"database/sql"
	"fmt"
	"log"
)

var db *sql.DB

func main() {
	age := 27
	rows, err := db.Query("SELECT name FROM users WHERE age=?", age)
	if err != nil {
		log.Fatal(err)
	}
	for rows.Next() {
		var name string
		if err := rows.Scan(&name); err != nil {
			log.Fatal(err)
		}
		fmt.Printf("%s is %d\n", name, age)
	}
	if err := rows.Err(); err != nil {
		log.Fatal(err)
	}
}

Output:

func (*DB) QueryRow 

func (db *DB) QueryRow(query string, args ...interface{}) *Row

QueryRow executes a query that is expected to return at most one row. QueryRow always return a non-nil value. Errors are deferred until Row's Scan method is called.

Example 
package main

import (
	"database/sql"
	"fmt"
	"log"
)

var db *sql.DB

func main() {
	id := 123
	var username string
	err := db.QueryRow("SELECT username FROM users WHERE id=?", id).Scan(&username)
	switch {
	case err == sql.ErrNoRows:
		log.Printf("No user with that ID.")
	case err != nil:
		log.Fatal(err)
	default:
		fmt.Printf("Username is %s\n", username)
	}
}

Output:

type NullBool 

type NullBool struct {
	Bool  bool
	Valid bool // Valid is true if Bool is not NULL
}

NullBool represents a bool that may be null. NullBool implements the Scanner interface so it can be used as a scan destination, similar to NullString.

func (*NullBool) Scan 

func (n *NullBool) Scan(value interface{}) error

Scan implements the Scanner interface.

func (NullBool) Value 

func (n NullBool) Value() (driver.Value, error)

Value implements the driver Valuer interface.

type NullFloat64 

type NullFloat64 struct {
	Float64 float64
	Valid   bool // Valid is true if Float64 is not NULL
}

NullFloat64 represents a float64 that may be null. NullFloat64 implements the Scanner interface so it can be used as a scan destination, similar to NullString.

func (*NullFloat64) Scan 

func (n *NullFloat64) Scan(value interface{}) error

Scan implements the Scanner interface.

func (NullFloat64) Value 

func (n NullFloat64) Value() (driver.Value, error)

Value implements the driver Valuer interface.

type NullInt64 

type NullInt64 struct {
	Int64 int64
	Valid bool // Valid is true if Int64 is not NULL
}

NullInt64 represents an int64 that may be null. NullInt64 implements the Scanner interface so it can be used as a scan destination, similar to NullString.

func (*NullInt64) Scan 

func (n *NullInt64) Scan(value interface{}) error

Scan implements the Scanner interface.

func (NullInt64) Value 

func (n NullInt64) Value() (driver.Value, error)

Value implements the driver Valuer interface.

type NullString 

type NullString struct {
	String string
	Valid  bool // Valid is true if String is not NULL
}

NullString represents a string that may be null. NullString implements the Scanner interface so it can be used as a scan destination: 

var s NullString
err := db.QueryRow("SELECT name FROM foo WHERE id=?", id).Scan(&s)
...
if s.Valid {
   // use s.String
} else {
   // NULL value
}

func (*NullString) Scan 

func (ns *NullString) Scan(value interface{}) error

Scan implements the Scanner interface.

func (NullString) Value 

func (ns NullString) Value() (driver.Value, error)

Value implements the driver Valuer interface.

type RawBytes 

type RawBytes []byte

RawBytes is a byte slice that holds a reference to memory owned by the database itself. After a Scan into a RawBytes, the slice is only valid until the next call to Next, Scan, or Close.

type Result 

type Result interface {
	LastInsertId() (int64, error)
	RowsAffected() (int64, error)
}

A Result summarizes an executed SQL command.

type Row 

type Row struct {
	// contains filtered or unexported fields
}

Row is the result of calling QueryRow to select a single row.

func (*Row) Scan 

func (r *Row) Scan(dest ...interface{}) error

Scan copies the columns from the matched row into the values pointed at by dest. If more than one row matches the query, Scan uses the first row and discards the rest. If no row matches the query, Scan returns ErrNoRows.

type Rows 

type Rows struct {
	// contains filtered or unexported fields
}

Rows is the result of a query. Its cursor starts before the first row of the result set. Use Next to advance through the rows: 

rows, err := db.Query("SELECT ...")
...
for rows.Next() {
    var id int
    var name string
    err = rows.Scan(&id, &name)
    ...
}
err = rows.Err() // get any error encountered during iteration
...

func (*Rows) Close 

func (rs *Rows) Close() error

Close closes the Rows, preventing further enumeration. If the end is encountered, the Rows are closed automatically. Close is idempotent.

func (*Rows) Columns 

func (rs *Rows) Columns() ([]string, error)

Columns returns the column names. Columns returns an error if the rows are closed, or if the rows are from QueryRow and there was a deferred error.

func (*Rows) Err 

func (rs *Rows) Err() error

Err returns the error, if any, that was encountered during iteration.

func (*Rows) Next 

func (rs *Rows) Next() bool

Next prepares the next result row for reading with the Scan method. It returns true on success, false if there is no next result row. Every call to Scan, even the first one, must be preceded by a call to Next.

func (*Rows) Scan 

func (rs *Rows) Scan(dest ...interface{}) error

Scan copies the columns in the current row into the values pointed at by dest.

If an argument has type *[]byte, Scan saves in that argument a copy of the corresponding data. The copy is owned by the caller and can be modified and held indefinitely. The copy can be avoided by using an argument of type *RawBytes instead; see the documentation for RawBytes for restrictions on its use.

If an argument has type *interface{}, Scan copies the value provided by the underlying driver without conversion. If the value is of type []byte, a copy is made and the caller owns the result.

type Scanner 

type Scanner interface {
	// Scan assigns a value from a database driver.
	//
	// The src value will be of one of the following restricted
	// set of types:
	//
	//    int64
	//    float64
	//    bool
	//    []byte
	//    string
	//    time.Time
	//    nil - for NULL values
	//
	// An error should be returned if the value can not be stored
	// without loss of information.
	Scan(src interface{}) error
}

Scanner is an interface used by Scan.

type Stmt 

type Stmt struct {
	// contains filtered or unexported fields
}

Stmt is a prepared statement. Stmt is safe for concurrent use by multiple goroutines.

func (*Stmt) Close 

func (s *Stmt) Close() error

Close closes the statement.

func (*Stmt) Exec 

func (s *Stmt) Exec(args ...interface{}) (Result, error)

Exec executes a prepared statement with the given arguments and returns a Result summarizing the effect of the statement.

func (*Stmt) Query 

func (s *Stmt) Query(args ...interface{}) (*Rows, error)

Query executes a prepared query statement with the given arguments and returns the query results as a *Rows.

func (*Stmt) QueryRow 

func (s *Stmt) QueryRow(args ...interface{}) *Row

QueryRow executes a prepared query statement with the given arguments. If an error occurs during the execution of the statement, that error will be returned by a call to Scan on the returned *Row, which is always non-nil. If the query selects no rows, the *Row's Scan will return ErrNoRows. Otherwise, the *Row's Scan scans the first selected row and discards the rest.

Example usage: 

var name string
err := nameByUseridStmt.QueryRow(id).Scan(&name)

type Tx 

type Tx struct {
	// contains filtered or unexported fields
}

Tx is an in-progress database transaction.

A transaction must end with a call to Commit or Rollback.

After a call to Commit or Rollback, all operations on the transaction fail with ErrTxDone.

func (*Tx) Commit 

func (tx *Tx) Commit() error

Commit commits the transaction.

func (*Tx) Exec 

func (tx *Tx) Exec(query string, args ...interface{}) (Result, error)

Exec executes a query that doesn't return rows. For example: an INSERT and UPDATE.

func (*Tx) Prepare 

func (tx *Tx) Prepare(query string) (*Stmt, error)

Prepare creates a prepared statement for use within a transaction.

The returned statement operates within the transaction and can no longer be used once the transaction has been committed or rolled back.

To use an existing prepared statement on this transaction, see Tx.Stmt.

func (*Tx) Query 

func (tx *Tx) Query(query string, args ...interface{}) (*Rows, error)

Query executes a query that returns rows, typically a SELECT.

func (*Tx) QueryRow 

func (tx *Tx) QueryRow(query string, args ...interface{}) *Row

QueryRow executes a query that is expected to return at most one row. QueryRow always return a non-nil value. Errors are deferred until Row's Scan method is called.

func (*Tx) Rollback 

func (tx *Tx) Rollback() error

Rollback aborts the transaction.

func (*Tx) Stmt 

func (tx *Tx) Stmt(stmt *Stmt) *Stmt

Stmt returns a transaction-specific prepared statement from an existing statement.

Example: 

updateMoney, err := db.Prepare("UPDATE balance SET money=money+? WHERE id=?")
...
tx, err := db.Begin()
...
res, err := tx.Stmt(updateMoney).Exec(123.45, 98293203)

Source Files

View all Source files

Directories

Path Synopsis
Package driver defines interfaces to be implemented by database drivers as used by package sql.
 Package driver defines interfaces to be implemented by database drivers as used by package sql.

Jump to

Keyboard shortcuts

? : This menu
/ : Search site
f or F : Jump to
y or Y : Canonical URL
go.dev uses cookies from Google to deliver and enhance the quality of its services and to analyze traffic. Learn more.