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tessl/maven-com-querydsl--querydsl-sql

SQL support for Querydsl - enables type-safe SQL query construction in Java

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QueryDSL SQL

QueryDSL SQL provides a fluent, type-safe API for building and executing SQL queries in Java. It eliminates SQL string concatenation by offering a programmatic query construction interface that supports complex queries, joins, subqueries, and database-specific optimizations while maintaining compile-time type safety.

Package Information

  • Package Name: com.querydsl:querydsl-sql
  • Package Type: maven
  • Language: Java
  • Installation: 
    <dependency>
  <groupId>com.querydsl</groupId>
  <artifactId>querydsl-sql</artifactId>
  <version>5.1.0</version>
</dependency>

Core Imports

import com.querydsl.sql.SQLQueryFactory;
import com.querydsl.sql.SQLQuery;
import com.querydsl.sql.Configuration;
import com.querydsl.sql.SQLTemplates;
import com.querydsl.sql.PostgreSQLTemplates;
import com.querydsl.core.Tuple;

Basic Usage

import com.querydsl.sql.*;
import com.querydsl.sql.postgresql.PostgreSQLTemplates;
import javax.sql.DataSource;

// Setup configuration with database-specific templates
SQLTemplates templates = PostgreSQLTemplates.builder().build();
Configuration configuration = new Configuration(templates);

// Create query factory
SQLQueryFactory queryFactory = new SQLQueryFactory(configuration, dataSource);

// Build and execute queries
List<String> names = queryFactory
    .select(qUser.name)
    .from(qUser)
    .where(qUser.active.isTrue())
    .fetch();

// DML operations
long count = queryFactory
    .update(qUser)
    .set(qUser.lastLogin, LocalDateTime.now())
    .where(qUser.id.eq(userId))
    .execute();

Architecture

QueryDSL SQL is built around several key components:

  • Query Factory: Central entry point (SQLQueryFactory) for creating queries and DML operations
  • Query Builders: Fluent interfaces (SQLQuery, AbstractSQLQuery) for constructing type-safe queries
  • SQL Templates: Database-specific dialect handling for 17+ databases with optimized SQL generation
  • Type System: Comprehensive type mapping between Java and SQL types with custom type support
  • DML Operations: Type-safe insert, update, delete, and merge operations with batch support
  • Configuration System: Flexible configuration for listeners, type mappings, and schema customization

Capabilities

Query Construction

Core query building functionality for SELECT statements with type-safe joins, conditions, grouping, and ordering. Supports complex queries including subqueries, CTEs, and window functions.

public SQLQuery<?> query();
public <T> SQLQuery<T> select(Expression<T> expr);
public SQLQuery<Tuple> select(Expression<?>... exprs);
public <T> SQLQuery<T> selectFrom(RelationalPath<T> expr);

Query Construction

Database Templates

Database-specific SQL dialect support with optimized templates for PostgreSQL, MySQL, Oracle, SQL Server, and 13+ other databases. Templates handle SQL syntax differences, function mappings, and database-specific features.

public abstract class SQLTemplates {
    public String getTypeNameForCode(int code);
    public boolean isArraysSupported();
    public boolean isLimitOffsetSupported();
}

public class PostgreSQLTemplates extends SQLTemplates;
public class MySQLTemplates extends SQLTemplates;
public class OracleTemplates extends SQLTemplates;

Database Templates

DML Operations

Type-safe Data Manipulation Language operations including INSERT, UPDATE, DELETE, and MERGE with batch processing support and automatic key generation.

public SQLInsertClause insert(RelationalPath<?> path);
public SQLUpdateClause update(RelationalPath<?> path);
public SQLDeleteClause delete(RelationalPath<?> path);
public SQLMergeClause merge(RelationalPath<?> path);

DML Operations

Type System

Comprehensive type mapping system between Java and SQL types with support for custom types, enums, arrays, and database-specific types like UUID, JSON, and XML.

public interface Type<T> {
    T getValue(ResultSet rs, int startIndex) throws SQLException;
    void setValue(PreparedStatement st, int startIndex, T value) throws SQLException;
    int[] getSQLTypes();
    Class<T> getReturnedClass();
}

Type System

Configuration and Customization

Flexible configuration system for customizing SQL generation, type mappings, naming strategies, schema mappings, and execution listeners.

public class Configuration {
    public Configuration(SQLTemplates templates);
    public void register(String table, String property, Path<?> path);
    public void registerType(String typeName, Type<?> type);
    public void addListener(SQLListener listener);
}

Configuration

SQL Expressions and Functions

Comprehensive expression builder for SQL functions, operators, and database-specific features including window functions, aggregate functions, and conditional expressions.

public class SQLExpressions {
    public static <T> SimpleExpression<T> constant(T value);
    public static StringExpression concat(Expression<String>... args);
    public static DateTimeExpression<Date> currentTimestamp();
    public static WindowFunction<Long> rowNumber();
}

SQL Expressions

Types

Core Query Interfaces

public interface SQLCommonQuery<Q> {
    List<Tuple> fetch();
    <T> List<T> fetch();
    Tuple fetchOne();
    <T> T fetchOne();
    long fetchCount();
}

public interface SQLCommonQueryFactory<Q, D, U, I, M> {
    Q query();
    D delete(RelationalPath<?> path);
    U update(RelationalPath<?> path);
    I insert(RelationalPath<?> path);
    M merge(RelationalPath<?> path);
}

Path and Metadata

public interface RelationalPath<T> extends Path<T> {
    SchemaAndTable getSchemaAndTable();
    Collection<? extends Path<?>> getColumns();
    PrimaryKey<T> getPrimaryKey();
}

public class SchemaAndTable {
    public SchemaAndTable(String schema, String table);
    public String getSchema();
    public String getTable();
}

Query Result Handling

public class SQLBindings {
    public String getSQL();
    public List<Object> getBindings();
}

public interface Union<T> {
    List<T> fetch();
    T fetchOne();
    Union<T> orderBy(OrderSpecifier<?>... o);
}
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mavenpkg:maven/com.querydsl/querydsl-sql@5.1.x
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