executor: add drop if exists warnings(close pingcap#7867)

Signed-off-by: Rustin-Liu <[email protected]>
Rustin170506 · Feb 16, 2020 · c2e4e2b · c2e4e2b
1 parent 63b71a3
commit c2e4e2b
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Showing 2 changed files with 17 additions and 0 deletions.
diff --git a/executor/ddl.go b/executor/ddl.go
@@ -334,6 +334,16 @@ func (e *DDLExec) dropTableObject(objects []*ast.TableName, obt objectType, ifEx
 		}
 		return infoschema.ErrTableDropExists.GenWithStackByArgs(strings.Join(notExistTables, ","))
 	}
+	// We need add warning when use if exists.
+	if len(notExistTables) > 0 && ifExists {
+		for _, table := range notExistTables {
+			if obt == sequenceObject {
+				e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrSequenceDropExists.GenWithStackByArgs(table))
+			} else {
+				e.ctx.GetSessionVars().StmtCtx.AppendNote(infoschema.ErrTableDropExists.GenWithStackByArgs(table))
+			}
+		}
+	}
 	return nil
 }
 

diff --git a/executor/ddl_test.go b/executor/ddl_test.go
@@ -1105,3 +1105,10 @@ func (s *testRecoverTable) TestRenameTable(c *C) {
 	tk.MustExec("drop database rename1")
 	tk.MustExec("drop database rename2")
 }
+
+func (s *testRecoverTable) TestDropTableIfExists(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t;")
+	tk.MustQuery("show warnings;").Check(testkit.Rows("Note 1051 Unknown table 'test.t'"))
+}