Database Support

The System.Data unit provides a database-agnostic layer for executing queries and managing data, with native support for SQLite.

DataBase Class

Method	Description
`Create(driver, params)`	Static factory (e.g., `DataBase.Create('SQLite', ['my.db'])`).
`Query(sql [, params])`	Executes SELECT and returns a `DataSet`.
`Exec(sql [, params])`	Executes non-query (INSERT/UPDATE/DELETE).
`BeginTransaction`	Starts a transaction.
`Commit / Rollback`	Transaction control.

DataSet Class

Member	Description
`Step`	Moves to next record and returns True if one exists. Practical for loops.
`Next`	Advances to next row. Returns False if EOF.
`Eof`	Returns True if the last record has been passed.
`FieldCount`	Number of columns in the result set.
`AsString(name/idx)`	Returns field value as string (using name or 0-based index).
`AsInteger(name/idx)`	Returns field value as integer.
`AsFloat(name/idx)`	Returns field value as float.
`IsNull(name/idx)`	Returns True if the field is NULL.
`StringifyAll`	Converts entire set to JSON array string.

Example: Querying SQLite

uses System.Data;

var db := DataBase.Create('SQLite', [':memory:']);
db.Exec('CREATE TABLE Users (ID INTEGER, Name TEXT)');
db.Exec('INSERT INTO Users VALUES (1, "Alice")');

var ds := db.Query('SELECT Name FROM Users');
while ds.Step do
  PrintLn(ds.AsString(0).ToHtml);

Result

Alice

Parameterized Updates

uses System.Data;
var db := DataBase.Create('SQLite', [':memory:']);
db.Exec('CREATE TABLE Users (ID INTEGER, Name TEXT)');
db.Exec('INSERT INTO Users VALUES (1, "Alice")');

db.Exec('UPDATE Users SET Name = ? WHERE ID = ?', ['Bob', 1]);

Driver Support

The SQLite driver is built-in. Other drivers can be registered by the host application to support PostgreSQL, MySQL, or SQL Server.

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