vlib: add a vlib/mssql module (#10280)

vlib/mssql/mssql.v

@@ -0,0 +1,122 @@
+module mssql
+
+pub struct Connection {
+mut:
+	henv C.SQLHENV = C.SQLHENV(C.SQL_NULL_HENV) // Environment
+	hdbc C.SQLHDBC = C.SQLHDBC(C.SQL_NULL_HDBC) // Connection handle
+pub mut:
+	conn_str string
+}
+
+// connect to db
+pub fn (mut conn Connection) connect(conn_str string) ?bool {
+	conn_str_c := unsafe { &C.SQLCHAR(conn_str.str) }
+	mut retcode := C.SQLRETURN(C.SQL_SUCCESS)
+	// Allocate environment handle
+	retcode = C.SQLAllocHandle(C.SQLSMALLINT(C.SQL_HANDLE_ENV), C.SQLHANDLE(C.SQL_NULL_HANDLE),
+		unsafe { &C.SQLHANDLE(&conn.henv) })
+	check_error(retcode, 'SQLAllocHandle(SQL_HANDLE_ENV)', C.SQLHANDLE(conn.henv), C.SQLSMALLINT(C.SQL_HANDLE_ENV)) ?
+
+	// Set the ODBC version environment attribute
+	retcode = C.SQLSetEnvAttr(conn.henv, C.SQLINTEGER(C.SQL_ATTR_ODBC_VERSION), &C.SQLPOINTER(C.SQL_OV_ODBC3),
+		C.SQLINTEGER(0))
+	check_error(retcode, 'SQLSetEnvAttr(SQL_ATTR_ODBC_VERSION)', C.SQLHANDLE(conn.henv),
+		C.SQLSMALLINT(C.SQL_HANDLE_ENV)) ?
+
+	// Allocate connection handle
+	retcode = C.SQLAllocHandle(C.SQLSMALLINT(C.SQL_HANDLE_DBC), C.SQLHANDLE(conn.henv),
+		unsafe { &C.SQLHANDLE(&conn.hdbc) })
+	check_error(retcode, 'SQLAllocHandle(SQL_HANDLE_DBC)', C.SQLHANDLE(conn.hdbc), C.SQLSMALLINT(C.SQL_HANDLE_DBC)) ?
+
+	// Set login timeout to 5 seconds
+	retcode = C.SQLSetConnectAttr(conn.hdbc, C.SQLINTEGER(C.SQL_LOGIN_TIMEOUT), C.SQLPOINTER(5),
+		C.SQLINTEGER(0))
+	check_error(retcode, 'SQLSetConnectAttr(SQL_LOGIN_TIMEOUT)', C.SQLHANDLE(conn.hdbc),
+		C.SQLSMALLINT(C.SQL_HANDLE_DBC)) ?
+
+	// Connect to data source
+	mut outstr := [1024]char{}
+	mut outstrlen := C.SQLSMALLINT(0)
+	retcode = C.SQLDriverConnect(conn.hdbc, C.SQLHWND(0), conn_str_c, C.SQLSMALLINT(C.SQL_NTS),
+		&C.SQLCHAR(&outstr[0]), C.SQLSMALLINT(sizeof(outstr)), &outstrlen, C.SQLUSMALLINT(C.SQL_DRIVER_NOPROMPT))
+	check_error(retcode, 'SQLDriverConnect()', C.SQLHANDLE(conn.hdbc), C.SQLSMALLINT(C.SQL_HANDLE_DBC)) ?
+	conn.conn_str = conn_str
+	return true
+}
+
+// close - closes the connection.
+pub fn (mut conn Connection) close() {
+	// Connection
+	if conn.hdbc != C.SQLHDBC(C.SQL_NULL_HDBC) {
+		C.SQLDisconnect(conn.hdbc)
+		C.SQLFreeHandle(C.SQLSMALLINT(C.SQL_HANDLE_DBC), C.SQLHANDLE(conn.hdbc))
+		conn.hdbc = C.SQLHDBC(C.SQL_NULL_HDBC)
+	}
+	// Environment
+	if conn.henv != C.SQLHENV(C.SQL_NULL_HENV) {
+		C.SQLFreeHandle(C.SQLSMALLINT(C.SQL_HANDLE_ENV), C.SQLHANDLE(conn.henv))
+		conn.henv = C.SQLHENV(C.SQL_NULL_HENV)
+	}
+}
+
+// query executes a sql query
+pub fn (mut conn Connection) query(q string) ?Result {
+	mut hstmt := new_hstmt(conn.hdbc) ?
+	defer {
+		hstmt.close()
+	}
+
+	hstmt.exec(q) ?
+
+	affected := hstmt.retrieve_affected_rows() ?
+
+	hstmt.prepare_read() ?
+	raw_rows := hstmt.read_rows() ?
+
+	mut res := Result{
+		rows: []Row{}
+		num_rows_affected: affected
+	}
+
+	for rr in raw_rows {
+		res.rows << Row{
+			vals: rr
+		}
+	}
+
+	return res
+}
+
+// check_error checks odbc return code and extract error string if available
+fn check_error(e C.SQLRETURN, s string, h C.SQLHANDLE, t C.SQLSMALLINT) ? {
+	if e != C.SQLRETURN(C.SQL_SUCCESS) && e != C.SQLRETURN(C.SQL_SUCCESS_WITH_INFO) {
+		err_str := extract_error(s, h, t)
+		return error(err_str)
+	}
+}
+
+// extract_error extracts error string from odbc
+fn extract_error(fnName string, handle C.SQLHANDLE, tp C.SQLSMALLINT) string {
+	mut err_str := fnName
+	mut i := 0
+	mut native_error := C.SQLINTEGER(0)
+	mut sql_state := [7]char{}
+	mut message_text := [256]char{}
+	mut text_length := C.SQLSMALLINT(0)
+	mut ret := C.SQLRETURN(C.SQL_SUCCESS)
+
+	for ret == C.SQLRETURN(C.SQL_SUCCESS) {
+		i++
+		ret = C.SQLGetDiagRec(tp, handle, C.SQLSMALLINT(i), &C.SQLCHAR(&sql_state[0]),
+			&native_error, &C.SQLCHAR(&message_text[0]), C.SQLSMALLINT(sizeof(message_text)),
+			&text_length)
+
+		// add driver error string
+		if ret == C.SQLRETURN(C.SQL_SUCCESS) || ret == C.SQLRETURN(C.SQL_SUCCESS_WITH_INFO) {
+			unsafe {
+				err_str += ':odbc=$(&sql_state[0]).vstring():$i:${int(native_error)}:$(&message_text[0]).vstring()\n'
+			}
+		}
+	}
+	return err_str
+}