Documentation
¶
Overview ¶
Package dialect provides typed SQL dialect identity and capability flags for GoSQLX. Use Capabilities() on a Dialect to feature-gate parser logic instead of string comparisons such as `p.dialect == "postgresql"`.
The typed Dialect constants in this package are the long-term replacement for scattered `p.dialect == "..."` comparisons in the parser. Consumers should prefer Dialect / Capabilities over string comparison so that:
- typos are caught at compile time;
- adding a new dialect is a single-file change (adding a case to Capabilities()) rather than a grep-audit of dozens of parser files;
- feature detection is intent-revealing ("supports QUALIFY") rather than implementation-coupled ("is Snowflake or BigQuery").
Backward compatibility:
- The parser.Parser struct keeps its string `dialect` field and its string-returning Dialect() method for the v1.x series.
- Migration happens call-site by call-site as scheduled for v2.0.
Index ¶
Constants ¶
This section is empty.
Variables ¶
This section is empty.
Functions ¶
This section is empty.
Types ¶
type Capabilities ¶
type Capabilities struct {
// SupportsQualify indicates QUALIFY clause support
// (Snowflake, BigQuery, Databricks, DuckDB).
SupportsQualify bool
// SupportsArrayJoin indicates ARRAY JOIN clause support (ClickHouse).
SupportsArrayJoin bool
// SupportsPrewhere indicates PREWHERE clause support (ClickHouse).
SupportsPrewhere bool
// SupportsSample indicates SAMPLE / TABLESAMPLE clause support
// (ClickHouse SAMPLE, standard TABLESAMPLE in PostgreSQL, SQL Server,
// Snowflake).
SupportsSample bool
// SupportsTimeTravel indicates AT/BEFORE time-travel clauses
// (Snowflake AT/BEFORE, Oracle FLASHBACK).
SupportsTimeTravel bool
// SupportsMatchRecognize indicates MATCH_RECOGNIZE row-pattern
// recognition (Oracle 12c+, Snowflake, Trino).
SupportsMatchRecognize bool
// SupportsPivotUnpivot indicates PIVOT / UNPIVOT support
// (Oracle 11g+, SQL Server, Snowflake, Databricks).
SupportsPivotUnpivot bool
// SupportsWindowIgnoreNulls indicates IGNORE NULLS / RESPECT NULLS in
// window functions (Oracle, Snowflake, SQL Server, Redshift, BigQuery).
SupportsWindowIgnoreNulls bool
// SupportsConnectBy indicates CONNECT BY / START WITH hierarchical
// queries (Oracle, Snowflake, MariaDB 10.2+).
SupportsConnectBy bool
// SupportsTop indicates TOP N row limiting
// (SQL Server, Snowflake, Sybase).
SupportsTop bool
// SupportsLimitOffset indicates LIMIT / OFFSET row limiting
// (PostgreSQL, MySQL, MariaDB, SQLite, ClickHouse, Snowflake,
// BigQuery, Redshift).
SupportsLimitOffset bool
// SupportsFetchFirst indicates standard SQL FETCH FIRST / OFFSET
// (Oracle 12c+, SQL Server 2012+, PostgreSQL, DB2).
SupportsFetchFirst bool
// SupportsMerge indicates MERGE statement support
// (SQL Server, Oracle, Snowflake, PostgreSQL 15+, BigQuery,
// ClickHouse 23.3+, MariaDB; NOT SQLite or classic MySQL).
SupportsMerge bool
// SupportsReturning indicates RETURNING clause on DML
// (PostgreSQL, Oracle, SQLite 3.35+, MariaDB, BigQuery).
SupportsReturning bool
// SupportsCompoundReturning indicates the SQL Server OUTPUT clause,
// which is similar to RETURNING but has different syntax and can emit
// into a result set or a table.
SupportsCompoundReturning bool
// SupportsDistinctOn indicates SELECT DISTINCT ON (...) syntax
// (PostgreSQL-only, not standard SQL).
SupportsDistinctOn bool
// SupportsMaterializedView indicates MATERIALIZED VIEW DDL
// (PostgreSQL, Oracle, Snowflake, ClickHouse, Redshift, BigQuery,
// Databricks).
SupportsMaterializedView bool
// SupportsIndexHints indicates MySQL-style USE INDEX / FORCE INDEX /
// IGNORE INDEX table hints (MySQL, MariaDB).
SupportsIndexHints bool
// SupportsBracketQuoting indicates [column] identifier quoting
// (SQL Server, MS Access).
SupportsBracketQuoting bool
// SupportsBacktickQuoting indicates `column` identifier quoting
// (MySQL, MariaDB, ClickHouse, BigQuery, Snowflake for some contexts).
SupportsBacktickQuoting bool
// SupportsDoubleQuoteIdentifier indicates "column" as identifier
// (standard SQL; supported by PostgreSQL, Oracle, SQLite, DB2,
// Snowflake, Redshift, and SQL Server with QUOTED_IDENTIFIER ON).
SupportsDoubleQuoteIdentifier bool
// SupportsILike indicates case-insensitive LIKE via the ILIKE operator
// (PostgreSQL, Snowflake, DuckDB, Redshift).
SupportsILike bool
}
Capabilities describes which optional SQL features a dialect supports. This is the long-term replacement for scattered `p.dialect == "..."` string comparisons in the parser.
Fields are intentionally kept to genuine feature-gated capabilities: each flag should correspond to at least one existing parser branch that would otherwise require string comparison. If a feature is supported by every dialect (e.g. SELECT, basic WHERE), it does not belong here.
type Dialect ¶
type Dialect string
Dialect is a typed SQL dialect identifier. The zero value is Unknown (empty string), which means "no dialect specified" and selects the permissive default capability set.
const ( // Unknown is the zero value; no dialect has been explicitly selected. // Matches the behaviour of an empty parser.dialect string field and // yields the permissive default capability set. Unknown Dialect = "" // PostgreSQL is the PostgreSQL dialect (https://www.postgresql.org/docs/). PostgreSQL Dialect = "postgresql" // MySQL is the MySQL / Percona dialect (https://dev.mysql.com/doc/). MySQL Dialect = "mysql" // MariaDB is the MariaDB dialect (https://mariadb.com/kb/en/). // Superset of MySQL 5.7 syntax plus SEQUENCE, system-versioned tables, // CONNECT BY, and index visibility controls. MariaDB Dialect = "mariadb" // SQLServer is Microsoft SQL Server / T-SQL // (https://learn.microsoft.com/sql/t-sql/). SQLServer Dialect = "sqlserver" // Oracle is Oracle Database / PL-SQL // (https://docs.oracle.com/en/database/oracle/oracle-database/). Oracle Dialect = "oracle" // SQLite is SQLite (https://www.sqlite.org/lang.html). SQLite Dialect = "sqlite" // Snowflake is Snowflake (https://docs.snowflake.com/). Snowflake Dialect = "snowflake" // ClickHouse is ClickHouse (https://clickhouse.com/docs/). ClickHouse Dialect = "clickhouse" // BigQuery is Google BigQuery // (https://cloud.google.com/bigquery/docs/reference/standard-sql/). BigQuery Dialect = "bigquery" // Redshift is Amazon Redshift // (https://docs.aws.amazon.com/redshift/latest/dg/). Redshift Dialect = "redshift" // Generic represents standard/ANSI SQL with no dialect-specific // features. It is distinct from Unknown: Generic explicitly means // "parse standard SQL only"; Unknown means "no choice has been made". Generic Dialect = "generic" )
Dialect constants. String values match the keywords.SQLDialect values to allow round-tripping through the legacy string field on the parser.
func Parse ¶
Parse normalises a free-form dialect string to a typed Dialect. The match is case-insensitive and tolerates a short list of well-known aliases ("postgres" -> PostgreSQL, "mssql" -> SQLServer). Unknown strings map to Unknown.
Empty input returns Unknown.
func (Dialect) Capabilities ¶
func (d Dialect) Capabilities() Capabilities
Capabilities returns the capability matrix for d.
For Unknown, the returned Capabilities is the "permissive default": flags that correspond to widely-supported standard SQL features are enabled so that callers who never call WithDialect keep working. Dialect-specific extensions (QUALIFY, ARRAY JOIN, PREWHERE, etc.) are disabled in the permissive default.
Source Files