Fix error while executing ALTER statement

`execute_bacth` should be used for DDL.
`execute` should still work except when `extra-check` feature is
activated.

src/lib.rs

@@ -1745,5 +1745,14 @@ mod test {
             )
             .unwrap();
         }
+
+        #[test]
+        #[cfg(not(feature = "extra_check"))]
+        fn test_alter_table() {
+            let db = checked_memory_handle();
+            db.execute_batch("CREATE TABLE x(t);").unwrap();
+            // `execute_batch` should be used but `execute` should also work
+            db.execute("ALTER TABLE x RENAME TO y;", params![]).unwrap();
+        }
     }
 }

src/statement.rs

@@ -515,13 +515,7 @@ impl Statement<'_> {
         let r = self.stmt.step();
         self.stmt.reset();
         match r {
-            ffi::SQLITE_DONE => {
+            ffi::SQLITE_DONE => Ok(self.conn.changes()),
-                if self.column_count() == 0 {
-                    Ok(self.conn.changes())
-                } else {
-                    Err(Error::ExecuteReturnedResults)
-                }
-            }
             ffi::SQLITE_ROW => Err(Error::ExecuteReturnedResults),
             _ => Err(self.conn.decode_result(r).unwrap_err()),
         }
@@ -551,6 +545,7 @@ impl Statement<'_> {
     #[cfg(all(feature = "modern_sqlite", feature = "extra_check"))]
     #[inline]
     fn check_update(&self) -> Result<()> {
+        // sqlite3_column_count works for DML but not for DDL (ie ALTER)
         if self.column_count() > 0 || self.stmt.readonly() {
             return Err(Error::ExecuteReturnedResults);
         }
@@ -560,6 +555,7 @@ impl Statement<'_> {
     #[cfg(all(not(feature = "modern_sqlite"), feature = "extra_check"))]
     #[inline]
     fn check_update(&self) -> Result<()> {
+        // sqlite3_column_count works for DML but not for DDL (ie ALTER)
         if self.column_count() > 0 {
             return Err(Error::ExecuteReturnedResults);
         }