Add sqlite3_database_unique_ptr::exec (initial author: Matthias Kuhn <matthias@opengis.ch>)

Partial backport of 49d8060
needed to backport e19bf11

Author: rouault

src/core/qgssqliteutils.cpp

@@ -91,6 +91,21 @@ sqlite3_statement_unique_ptr sqlite3_database_unique_ptr::prepare( const QString
   return s;
 }
 
+int sqlite3_database_unique_ptr::exec( const QString &sql, QString &errorMessage ) const
+{
+  char *errMsg;
+
+  int ret = sqlite3_exec( get(), sql.toUtf8(), nullptr, nullptr, &errMsg );
+
+  if ( errMsg )
+  {
+    errorMessage = QString::fromUtf8( errMsg );
+    sqlite3_free( errMsg );
+  }
+
+  return ret;
+}
+
 QString QgsSqliteUtils::quotedString( const QString &value )
 {
   if ( value.isNull() )

src/core/qgssqliteutils.h

@@ -21,6 +21,8 @@
 #define SIP_NO_FILE
 
 #include "qgis_core.h"
+#include "qgis_sip.h"
+
 #include <memory>
 #include <QString>
 
@@ -134,8 +136,17 @@ class CORE_EXPORT sqlite3_database_unique_ptr : public std::unique_ptr< sqlite3,
      * Prepares a \a sql statement, returning the result. The \a resultCode
      * argument will be filled with the sqlite3 result code.
      */
-    sqlite3_statement_unique_ptr prepare( const QString &sql, int &resultCode ) const;
+    sqlite3_statement_unique_ptr prepare( const QString &sql, int &resultCode SIP_OUT ) const;
 
+    /**
+     * Executes the \a sql command in the database. Multiple sql queries can be run within
+     * one single command.
+     * Errors are reported to \a errorMessage.
+     * Returns SQLITE_OK in case of success or an sqlite error code.
+     *
+     * \since QGIS 3.4.5
+     */
+    int exec( const QString &sql, QString &errorMessage SIP_OUT ) const;
 };
 
 /**