executor: support "show create table" for View (#8865)

ddl/ddl_api.go

@@ -1104,6 +1104,16 @@ func (d *ddl) CreateView(ctx sessionctx.Context, s *ast.CreateViewStmt) (err err
 		BinlogInfo: &model.HistoryInfo{},
 		Args:       []interface{}{tbInfo, s.OrReplace},
 	}
+	if v, ok := ctx.GetSessionVars().GetSystemVar("character_set_client"); ok {
+		tbInfo.Charset = v
+	}
+	if v, ok := ctx.GetSessionVars().GetSystemVar("collation_connection"); ok {
+		tbInfo.Collate = v
+	}
+	err = checkCharsetAndCollation(tbInfo.Charset, tbInfo.Collate)
+	if err != nil {
+		return errors.Trace(err)
+	}
 	err = d.doDDLJob(ctx, job)
 
 	return d.callHookOnChanged(err)

executor/show.go

@@ -584,6 +584,12 @@ func (e *ShowExec) fetchShowCreateTable() error {
 
 	// TODO: let the result more like MySQL.
 	var buf bytes.Buffer
+	if tb.Meta().IsView() {
+		e.fetchShowCreateTable4View(tb.Meta(), &buf)
+		e.appendRow([]interface{}{tb.Meta().Name.O, buf.String(), tb.Meta().Charset, tb.Meta().Collate})
+		return nil
+	}
+
 	fmt.Fprintf(&buf, "CREATE TABLE %s (\n", escape(tb.Meta().Name, sqlMode))
 	var pkCol *table.Column
 	var hasAutoIncID bool
@@ -733,11 +739,26 @@ func (e *ShowExec) fetchShowCreateTable() error {
 	if len(tb.Meta().Comment) > 0 {
 		fmt.Fprintf(&buf, " COMMENT='%s'", format.OutputFormat(tb.Meta().Comment))
 	}
-
 	e.appendRow([]interface{}{tb.Meta().Name.O, buf.String()})
 	return nil
 }
 
+func (e *ShowExec) fetchShowCreateTable4View(tb *model.TableInfo, buf *bytes.Buffer) {
+	sqlMode := e.ctx.GetSessionVars().SQLMode
+
+	fmt.Fprintf(buf, "CREATE ALGORITHM=%s ", tb.View.Algorithm.String())
+	fmt.Fprintf(buf, "DEFINER=%s@%s ", escape(model.NewCIStr(tb.View.Definer.Username), sqlMode), escape(model.NewCIStr(tb.View.Definer.Hostname), sqlMode))
+	fmt.Fprintf(buf, "SQL SECURITY %s ", tb.View.Security.String())
+	fmt.Fprintf(buf, "VIEW %s (", escape(tb.Name, sqlMode))
+	for i, col := range tb.Columns {
+		fmt.Fprintf(buf, "%s", escape(col.Name, sqlMode))
+		if i < len(tb.Columns)-1 {
+			fmt.Fprintf(buf, ", ")
+		}
+	}
+	fmt.Fprintf(buf, ") AS %s", tb.View.SelectStmt)
+}
+
 func appendPartitionInfo(partitionInfo *model.PartitionInfo, buf *bytes.Buffer) {
 	if partitionInfo == nil {
 		return

executor/show_test.go

@@ -300,6 +300,20 @@ func (s *testSuite2) TestShowSlow(c *C) {
 	tk.MustQuery(`admin show slow top all 3`)
 }
 
+func (s *testSuite2) TestShowCreateTable(c *C) {
+	tk := testkit.NewTestKit(c, s.store)
+
+	tk.MustExec("use test")
+	tk.MustExec("drop table if exists t1")
+	tk.MustExec("create table t1(a int,b int)")
+	tk.MustExec("drop view if exists v1")
+	tk.MustExec("create or replace definer=`root`@`127.0.0.1` view v1 as select * from t1")
+	tk.MustQuery("show create table v1").Check(testutil.RowsWithSep("|", "v1|CREATE ALGORITHM=UNDEFINED DEFINER=`root`@`127.0.0.1` SQL SECURITY DEFINER VIEW `v1` (`a`, `b`) AS select * from t1  "))
+
+	tk.MustExec("drop view v1")
+	tk.MustExec("drop table t1")
+}
+
 func (s *testSuite2) TestShowEscape(c *C) {
 	tk := testkit.NewTestKit(c, s.store)
 

planner/core/planbuilder.go

@@ -936,15 +936,19 @@ func (b *PlanBuilder) buildShow(show *ast.ShowStmt) (Plan, error) {
 	case ast.ShowWarnings, ast.ShowErrors:
 		p.SetSchema(buildShowWarningsSchema())
 	default:
+		isView := false
 		switch showTp {
 		case ast.ShowTables, ast.ShowTableStatus:
 			if p.DBName == "" {
 				return nil, ErrNoDB
 			}
 		case ast.ShowCreateTable:
 			b.visitInfo = appendVisitInfo(b.visitInfo, mysql.AllPrivMask, show.Table.Schema.L, show.Table.Name.L, "", nil)
+			if table, err := b.is.TableByName(show.Table.Schema, show.Table.Name); err == nil {
+				isView = table.Meta().IsView()
+			}
 		}
-		p.SetSchema(buildShowSchema(show))
+		p.SetSchema(buildShowSchema(show, isView))
 	}
 	for _, col := range p.schema.Columns {
 		col.UniqueID = b.ctx.GetSessionVars().AllocPlanColumnID()
@@ -1667,7 +1671,7 @@ func buildShowWarningsSchema() *expression.Schema {
 }
 
 // buildShowSchema builds column info for ShowStmt including column name and type.
-func buildShowSchema(s *ast.ShowStmt) (schema *expression.Schema) {
+func buildShowSchema(s *ast.ShowStmt, isView bool) (schema *expression.Schema) {
 	var names []string
 	var ftypes []byte
 	switch s.Tp {
@@ -1704,7 +1708,11 @@ func buildShowSchema(s *ast.ShowStmt) (schema *expression.Schema) {
 		ftypes = []byte{mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong,
 			mysql.TypeVarchar, mysql.TypeVarchar, mysql.TypeLonglong}
 	case ast.ShowCreateTable:
-		names = []string{"Table", "Create Table"}
+		if !isView {
+			names = []string{"Table", "Create Table"}
+		} else {
+			names = []string{"View", "Create View", "character_set_client", "collation_connection"}
+		}
 	case ast.ShowCreateDatabase:
 		names = []string{"Database", "Create Database"}
 	case ast.ShowGrants:

planner/core/planbuilder_test.go

@@ -52,7 +52,7 @@ func (s *testPlanBuilderSuite) TestShow(c *C) {
 	}
 	for _, tp := range tps {
 		node.Tp = tp
-		schema := buildShowSchema(node)
+		schema := buildShowSchema(node, false)
 		for _, col := range schema.Columns {
 			c.Assert(col.RetType.Flen, Greater, 0)
 		}