org.apache.calcite.sql

Class SqlDialect

java.lang.Object

org.apache.calcite.sql.SqlDialect

public class SqlDialect
extends Object

SqlDialect encapsulates the differences between dialects of SQL.

It is used by classes such as SqlWriter and SqlBuilder.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	SqlDialect.DatabaseProduct Rough list of flavors of database.
static class	SqlDialect.FakeUtil A few utility functions copied from org.apache.calcite.util.Util.

Field Summary

Fields

Modifier and Type	Field and Description
static SqlDialect	CALCITE A dialect useful for generating SQL which can be parsed by the Calcite parser, in particular quoting literals and identifiers.
static SqlDialect	DUMMY A dialect useful for generating generic SQL.

Constructor Summary

Constructors

Constructor and Description
SqlDialect(SqlDialect.DatabaseProduct databaseProduct, String databaseProductName, String identifierQuoteString) Creates a SqlDialect.

Method Summary

Methods

Modifier and Type	Method and Description
protected boolean	allowsAs()
static SqlDialect	create(DatabaseMetaData databaseMetaData) Creates a SqlDialect from a DatabaseMetaData.
SqlDialect.DatabaseProduct	getDatabaseProduct() Returns the database this dialect belongs to, SqlDialect.DatabaseProduct.UNKNOWN if not known, never null.
static SqlDialect.DatabaseProduct	getProduct(String productName, String productVersion) Converts a product name and version (per the JDBC driver) into a product enumeration.
boolean	identifierNeedsToBeQuoted(String val) Returns whether a given identifier needs to be quoted.
String	quoteIdentifier(String val) Encloses an identifier in quotation marks appropriate for the current SQL dialect.
StringBuilder	quoteIdentifier(StringBuilder buf, List<String> identifiers) Quotes a multi-part identifier.
StringBuilder	quoteIdentifier(StringBuilder buf, String val) Encloses an identifier in quotation marks appropriate for the current SQL dialect, writing the result to a StringBuilder.
String	quoteStringLiteral(String val) Converts a string into a string literal.
void	quoteStringLiteralUnicode(StringBuilder buf, String val) Converts a string into a unicode string literal.
String	quoteTimestampLiteral(Timestamp timestamp) Converts a timestamp to a SQL timestamp literal, e.g.
protected boolean	requiresAliasForFromItems()
boolean	supportsCharSet() Returns whether the dialect supports character set names as part of a data type, for instance VARCHAR(30) CHARACTER SET `ISO-8859-1`.
String	unquoteStringLiteral(String val) Converts a string literal back into a string.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

DUMMY

public static final SqlDialect DUMMY

A dialect useful for generating generic SQL. If you need to do something database-specific like quoting identifiers, don't rely on this dialect to do what you want.

CALCITE

public static final SqlDialect CALCITE

A dialect useful for generating SQL which can be parsed by the Calcite parser, in particular quoting literals and identifiers. If you want a dialect that knows the full capabilities of the database, create one from a connection.

Constructor Detail

SqlDialect

public SqlDialect(SqlDialect.DatabaseProduct databaseProduct,
          String databaseProductName,
          String identifierQuoteString)

Creates a SqlDialect.

Parameters:

databaseProduct - Database product; may be UNKNOWN, never null

databaseProductName - Database product name from JDBC driver

identifierQuoteString - String to quote identifiers. Null if quoting is not supported. If "[", close quote is deemed to be "]".

Method Detail

create

public static SqlDialect create(DatabaseMetaData databaseMetaData)

Creates a SqlDialect from a DatabaseMetaData.

Does not maintain a reference to the DatabaseMetaData -- or, more importantly, to its Connection -- after this call has returned.

Parameters:

databaseMetaData - used to determine which dialect of SQL to generate

getProduct

public static SqlDialect.DatabaseProduct getProduct(String productName,
                                    String productVersion)

Converts a product name and version (per the JDBC driver) into a product enumeration.

Parameters:

productName - Product name

productVersion - Product version

Returns:

database product

quoteIdentifier

public String quoteIdentifier(String val)

Encloses an identifier in quotation marks appropriate for the current SQL dialect.

For example, quoteIdentifier("emp") yields a string containing "emp" in Oracle, and a string containing [emp] in Access.

Parameters:

val - Identifier to quote

Returns:

Quoted identifier

quoteIdentifier

public StringBuilder quoteIdentifier(StringBuilder buf,
                            String val)

Encloses an identifier in quotation marks appropriate for the current SQL dialect, writing the result to a StringBuilder.

For example, quoteIdentifier("emp") yields a string containing "emp" in Oracle, and a string containing [emp] in Access.

Parameters:

buf - Buffer

val - Identifier to quote

Returns:

The buffer

quoteIdentifier

public StringBuilder quoteIdentifier(StringBuilder buf,
                            List<String> identifiers)

Quotes a multi-part identifier.

Parameters:

buf - Buffer

identifiers - List of parts of the identifier to quote

Returns:

The buffer

identifierNeedsToBeQuoted

public boolean identifierNeedsToBeQuoted(String val)

Returns whether a given identifier needs to be quoted.

quoteStringLiteral

public String quoteStringLiteral(String val)

Converts a string into a string literal. For example, can't run becomes 'can''t run'.

quoteStringLiteralUnicode

public void quoteStringLiteralUnicode(StringBuilder buf,
                             String val)

Converts a string into a unicode string literal. For example, can't{tab}run\ becomes u'can''t\0009run\\'.

unquoteStringLiteral

public String unquoteStringLiteral(String val)

Converts a string literal back into a string. For example, 'can''t run' becomes can't run.

allowsAs

protected boolean allowsAs()

requiresAliasForFromItems

protected boolean requiresAliasForFromItems()

quoteTimestampLiteral

public String quoteTimestampLiteral(Timestamp timestamp)

Converts a timestamp to a SQL timestamp literal, e.g. TIMESTAMP '2009-12-17 12:34:56'.

Timestamp values do not have a time zone. We therefore interpret them as the number of milliseconds after the UTC epoch, and the formatted value is that time in UTC.

In particular,

quoteTimestampLiteral(new Timestamp(0));

returns TIMESTAMP '1970-01-01 00:00:00', regardless of the JVM's timezone.

Parameters:

timestamp - Timestamp

Returns:

SQL timestamp literal

getDatabaseProduct

public SqlDialect.DatabaseProduct getDatabaseProduct()

Returns the database this dialect belongs to, SqlDialect.DatabaseProduct.UNKNOWN if not known, never null.

Returns:

Database product

supportsCharSet

public boolean supportsCharSet()

Returns whether the dialect supports character set names as part of a data type, for instance VARCHAR(30) CHARACTER SET `ISO-8859-1`.