Documentation
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Overview ¶
Package dialect contains functionality for SQL dialects.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
func DefaultOps ¶
DefaultOps returns a default map of SLQ operator (e.g. "==" or "!=") to its SQL rendering. The returned map is a copy and can be safely modified by the caller. This function is intended for use by driver initialization code; callers should use Dialect.Ops instead.
Types ¶
type Dialect ¶
type Dialect struct {
// Placeholders returns a string a SQL placeholders string.
// For example "(?, ?, ?)" or "($1, $2, $3), ($4, $5, $6)".
Placeholders func(numCols, numRows int) string
// Enquote is a function that quotes and escapes an
// identifier (such as a table or column name). Typically, the func
// uses the double-quote rune (although MySQL uses backtick).
Enquote func(string) string
// ExecModeFor returns the ExecMode for a SQL string. The default
// implementation is DefaultExecModeFor, which handles standard SQL.
// This is a function pointer to allow drivers to override exec mode
// detection if a dialect has non-standard rules (e.g., vendor-specific
// keywords that return rows).
ExecModeFor func(sql string) (ExecMode, error)
// Ops is a map of SLQ operator (e.g. "==" or "!=") to its SQL rendering.
// The default implementation is DefaultOps, which handles standard SQL
// operators. Drivers can override specific operators if a dialect has
// non-standard mappings.
Ops map[string]string
// Type is the dialect's driver type.
Type drivertype.Type `json:"type"`
// Joins is the set of JOIN types (e.g. "RIGHT JOIN") that
// the dialect supports. Not all drivers support each join type. For
// example, MySQL doesn't support jointype.FullOuter.
Joins []jointype.Type
// MaxBatchValues is the maximum number of values in a batch insert.
MaxBatchValues int
// IntBool is true if BOOLEAN is handled as an INT by the DB driver.
IntBool bool `json:"int_bool"`
// Catalog indicates that the database supports the catalog concept,
// in addition to schema. For example, PostgreSQL supports catalog
// and schema (sakila.public.actor), whereas MySQL only supports schema
// (sakila.actor).
Catalog bool
}
Dialect holds driver-specific SQL dialect values and functions. The zero value is not usable; each driver implementation must initialize all fields appropriately. See the driver packages (e.g., postgres, mysql) for examples.
type ExecMode ¶ added in v0.48.11
type ExecMode string
ExecMode indicates whether a SQL statement should be executed via DB.Query (returns rows) or DB.Exec (returns affected count).
The naming follows Go's database/sql package conventions, where DB.Query returns rows and DB.Exec returns an affected count. Alternative names like "Statement" were considered but rejected: all SQL is technically a statement, and Go's *sql.Stmt specifically means a prepared statement. The usql project (github.com/xo/usql) uses similar "query" vs "exec" terminology.
See also: https://pkg.go.dev/database/sql
const ( // ExecModeQuery indicates a SQL query that returns rows, such as SELECT. // Use DB.QueryContext for this mode. ExecModeQuery ExecMode = "query" // ExecModeExec indicates a SQL statement that does not return rows, such as // INSERT, UPDATE, DELETE, CREATE, DROP, etc. Use DB.ExecContext for this // mode. ExecModeExec ExecMode = "exec" )
func DefaultExecModeFor ¶ added in v0.48.11
DefaultExecModeFor returns the ExecMode for a SQL string. It uses the usql library (github.com/xo/usql) to determine whether the SQL should be executed via DB.Query (returns rows) or DB.Exec (returns affected count). An error is returned if the SQL string is empty, contains only whitespace/comments, or is invalid/unparseable such that usql's FindPrefix cannot determine a statement prefix. This function is intended for use by driver initialization code; callers should use Dialect.ExecModeFor instead.
See also: https://pkg.go.dev/github.com/xo/usql/drivers#QueryExecType
Source Files