Dialects

Dew supports multiple SQL dialects. A dialect controls how query placeholders are rendered.

Available dialects

Dialect	Struct	Placeholders	Example
PostgreSQL	`dew.PostgreSQLDialect{}`	`$1, $2, $3`	`WHERE id = $1`
MySQL	`dew.MySQLDialect{}`	`?, ?, ?`	`WHERE id = ?`
SQLite	`dew.SQLiteDialect{}`	`?, ?, ?`	`WHERE id = ?`
MSSQL	`dew.MSSQLDialect{}`	`@p1, @p2, @p3`	`WHERE id = @p1`

Pass a dialect when opening a connection:

db, err := dew.Open("postgres", dsn, dew.PostgreSQLDialect{})

And when defining schemas:

var Users = dew.DefineSchema("users", dew.PostgreSQLDialect{}, func(t dew.Table[User]) struct {
    // ...
})

type Dialect interface {
    Placeholder(index int) string
}

The index is zero-based. PostgreSQL's Placeholder(0) returns "$1", Placeholder(1) returns "$2", etc.

Implement the Dialect interface to support other databases:

type OracleDialect struct{}

func (d OracleDialect) Placeholder(index int) string {
    return fmt.Sprintf(":p%d", index+1)
}

Then use it like any built-in dialect:

db, err := dew.Open("oracle", dsn, OracleDialect{})