Demonstrates the fluent query builder API for constructing SQL queries. More...

#include <iostream>
#include <string>
#include <vector>
#include <map>
#include "database/query_builder.h"
#include "database/database_types.h"

Include dependency graph for query_builder_usage.cpp:

Go to the source code of this file.

Functions
int	main ()

Detailed Description

Demonstrates the fluent query builder API for constructing SQL queries.

This example shows how to:

Build SELECT queries with WHERE, ORDER BY, LIMIT, and OFFSET
Build INSERT queries with column-value maps
Build UPDATE queries with SET and WHERE clauses
Build DELETE queries with conditions
Use JOIN, GROUP BY, and HAVING clauses
Use query_condition objects with logical operators

Note: This example generates SQL strings without executing them. It does not require a running database and is useful for understanding the query builder API.

Definition in file query_builder_usage.cpp.

Function Documentation

◆ main()

int main ( )

Definition at line 32 of file query_builder_usage.cpp.

{
    std::cout << "=== query_builder_usage example ===" << std::endl;
 
    // -------------------------------------------------------
    // 1. SELECT query
    // -------------------------------------------------------
    std::cout << "\n--- SELECT ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto query = builder.select({"id", "name", "email"})
                         .from("users")
                         .where("age", ">=", int64_t{18})
                         .where("is_active", "=", true)
                         .order_by("name", sort_order::asc)
                         .limit(20)
                         .offset(0)
                         .build();
 
        std::cout << "SELECT query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 2. INSERT query
    // -------------------------------------------------------
    std::cout << "\n--- INSERT ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        std::map<std::string, core::database_value> row;
        row["name"] = std::string("Alice");
        row["email"] = std::string("alice@example.com");
        row["age"] = int64_t{30};
        row["is_active"] = true;
 
        auto query = builder.insert_into("users").values(row).build();
 
        std::cout << "INSERT query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 3. Batch INSERT query
    // -------------------------------------------------------
    std::cout << "\n--- Batch INSERT ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        std::vector<std::map<std::string, core::database_value>> rows;
 
        std::map<std::string, core::database_value> row1;
        row1["name"] = std::string("Bob");
        row1["email"] = std::string("bob@example.com");
        row1["age"] = int64_t{25};
        rows.push_back(row1);
 
        std::map<std::string, core::database_value> row2;
        row2["name"] = std::string("Carol");
        row2["email"] = std::string("carol@example.com");
        row2["age"] = int64_t{28};
        rows.push_back(row2);
 
        auto query = builder.insert_into("users").values(rows).build();
 
        std::cout << "Batch INSERT query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 4. UPDATE query
    // -------------------------------------------------------
    std::cout << "\n--- UPDATE ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto query = builder.update("users")
                         .set("email", std::string("newalice@example.com"))
                         .set("age", int64_t{31})
                         .where("name", "=", std::string("Alice"))
                         .build();
 
        std::cout << "UPDATE query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 5. DELETE query
    // -------------------------------------------------------
    std::cout << "\n--- DELETE ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto query = builder.delete_from("users")
                         .where("is_active", "=", false)
                         .build();
 
        std::cout << "DELETE query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 6. JOIN query
    // -------------------------------------------------------
    std::cout << "\n--- JOIN ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto query = builder.select({"u.name", "o.total"})
                         .from("users u")
                         .join("orders o", "u.id = o.user_id", join_type::inner)
                         .where("o.total", ">", 100.0)
                         .order_by("o.total", sort_order::desc)
                         .build();
 
        std::cout << "JOIN query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 7. GROUP BY with HAVING
    // -------------------------------------------------------
    std::cout << "\n--- GROUP BY ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto query = builder.select({"department", "COUNT(*) AS cnt"})
                         .from("employees")
                         .group_by("department")
                         .having("COUNT(*) > 5")
                         .order_by("cnt", sort_order::desc)
                         .build();
 
        std::cout << "GROUP BY query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 8. Compound conditions with query_condition
    // -------------------------------------------------------
    std::cout << "\n--- Compound conditions ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        // Build individual conditions
        query_condition age_check("age", ">=", int64_t{21});
        query_condition active_check("is_active", "=", true);
 
        // Combine with logical AND
        auto combined = age_check && active_check;
 
        auto query = builder.select({"*"}).from("users").where(combined).build();
 
        std::cout << "Compound condition query:\n  " << query << std::endl;
    }
 
    // -------------------------------------------------------
    // 9. Switching database dialect
    // -------------------------------------------------------
    std::cout << "\n--- Dialect switch ---" << std::endl;
    {
        query_builder builder(database_types::postgres);
 
        auto pg_query = builder.select({"id", "name"})
                            .from("users")
                            .where("id", "=", int64_t{1})
                            .build();
        std::cout << "PostgreSQL: " << pg_query << std::endl;
 
        // Reset and switch dialect to SQLite
        builder.reset();
        builder.for_database(database_types::sqlite);
 
        auto sqlite_query = builder.select({"id", "name"})
                               .from("users")
                               .where("id", "=", int64_t{1})
                               .build();
        std::cout << "SQLite:     " << sqlite_query << std::endl;
    }
 
    std::cout << "\n=== query_builder_usage example completed ===" << std::endl;
    return 0;
}

Here is the call graph for this function:

Functions

Detailed Description

Function Documentation

◆ main()