planner,executor: support show create database if not exists syntax

executor/builder.go

@@ -502,6 +502,7 @@ func (b *executorBuilder) buildShow(v *plannercore.Show) Executor {
  Table: v.Table,
  Column: v.Column,
  User: v.User,
+ IfNotExists: v.IfNotExists,
  Flag: v.Flag,
  Full: v.Full,
  GlobalScope: v.GlobalScope,

executor/seqtest/seq_executor_test.go

@@ -333,7 +333,11 @@ func (s *seqTestSuite) TestShow(c *C) {
  tk.MustExec(testSQL)
  testSQL = "show create database show_test_DB;"
  tk.MustQuery(testSQL).Check(testutil.RowsWithSep("|",
- "show_test_DB|CREATE DATABASE `show_test_DB` /* !40100 DEFAULT CHARACTER SET utf8mb4 */",
+ "show_test_DB|CREATE DATABASE `show_test_DB` /*!40100 DEFAULT CHARACTER SET utf8mb4 */",
+ ))
+ testSQL = "show create database if not exists show_test_DB;"
+ tk.MustQuery(testSQL).Check(testutil.RowsWithSep("|",
+ "show_test_DB|CREATE DATABASE /*!32312 IF NOT EXISTS*/ `show_test_DB` /*!40100 DEFAULT CHARACTER SET utf8mb4 */",
  ))
 
  tk.MustExec("use show_test_DB")

executor/show.go

@@ -46,13 +46,14 @@ import (
 type ShowExec struct {
  baseExecutor
 
- Tp ast.ShowStmtType // Databases/Tables/Columns/....
- DBName model.CIStr
- Table *ast.TableName // Used for showing columns.
- Column *ast.ColumnName // Used for `desc table column`.
- Flag int // Some flag parsed from sql, such as FULL.
- Full bool
- User *auth.UserIdentity // Used for show grants.
+ Tp ast.ShowStmtType // Databases/Tables/Columns/....
+ DBName model.CIStr
+ Table *ast.TableName // Used for showing columns.
+ Column *ast.ColumnName // Used for `desc table column`.
+ Flag int // Some flag parsed from sql, such as FULL.
+ Full bool
+ User *auth.UserIdentity // Used for show grants.
+ IfNotExists bool // Used for `show create database if not exists`
 
  // GlobalScope is used by show variables
  GlobalScope bool
@@ -764,9 +765,13 @@ func (e *ShowExec) fetchShowCreateDatabase() error {
  sqlMode := e.ctx.GetSessionVars().SQLMode
 
  var buf bytes.Buffer
- fmt.Fprintf(&buf, "CREATE DATABASE %s", escape(db.Name, sqlMode))
+ var ifNotExists string
+ if e.IfNotExists {
+ ifNotExists = "/*!32312 IF NOT EXISTS*/ "
+ }
+ fmt.Fprintf(&buf, "CREATE DATABASE %s%s", ifNotExists, escape(db.Name, sqlMode))
  if s := db.Charset; len(s) > 0 {
- fmt.Fprintf(&buf, " /* !40100 DEFAULT CHARACTER SET %s */", s)
+ fmt.Fprintf(&buf, " /*!40100 DEFAULT CHARACTER SET %s */", s)
  }
 
  e.appendRow([]interface{}{db.Name.O, buf.String()})

go.mod

@@ -48,7 +48,7 @@ require (
  github.com/pingcap/gofail v0.0.0-20181217135706-6a951c1e42c3
  github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e
  github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c
- github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641
+ github.com/pingcap/parser v0.0.0-20190103131433-5d5a6dd34655
  github.com/pingcap/pd v2.1.0-rc.4+incompatible
  github.com/pingcap/tidb-tools v2.1.1-0.20181218072513-b2235d442b06+incompatible
  github.com/pingcap/tipb v0.0.0-20181012112600-11e33c750323

go.sum

@@ -110,8 +110,8 @@ github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e h1:P73/4dPCL96rG
 github.com/pingcap/goleveldb v0.0.0-20171020122428-b9ff6c35079e/go.mod h1:O17XtbryoCJhkKGbT62+L2OlrniwqiGLSqrmdHCMzZw=
 github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c h1:Qf5St5XGwKgKQLar9lEXoeO0hJMVaFBj3JqvFguWtVg=
 github.com/pingcap/kvproto v0.0.0-20181203065228-c14302da291c/go.mod h1:Ja9XPjot9q4/3JyCZodnWDGNXt4pKemhIYCvVJM7P24=
-github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641 h1:KTGU8kr2wY+FRiHHs8I5lp385b+OzYnbOr3/tPVw7mU=
-github.com/pingcap/parser v0.0.0-20190103075927-c065c7404641/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
+github.com/pingcap/parser v0.0.0-20190103131433-5d5a6dd34655 h1:nAGxJRuzO6T7mL/uAaOOZSVl9x+Vmy6cTYuzQjFDRw4=
+github.com/pingcap/parser v0.0.0-20190103131433-5d5a6dd34655/go.mod h1:1FNvfp9+J0wvc4kl8eGNh7Rqrxveg15jJoWo/a0uHwA=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible h1:/buwGk04aHO5odk/+O8ZOXGs4qkUjYTJ2UpCJXna8NE=
 github.com/pingcap/pd v2.1.0-rc.4+incompatible/go.mod h1:nD3+EoYes4+aNNODO99ES59V83MZSI+dFbhyr667a0E=
 github.com/pingcap/tidb-tools v2.1.1-0.20181218072513-b2235d442b06+incompatible h1:Bsd+NHosPVowEGB3BCx+2d8wUQGDTXSSC5ljeNS6cXo=

planner/core/common_plans.go

@@ -305,13 +305,14 @@ type Deallocate struct {
 type Show struct {
  baseSchemaProducer
 
- Tp ast.ShowStmtType // Databases/Tables/Columns/....
- DBName string
- Table *ast.TableName // Used for showing columns.
- Column *ast.ColumnName // Used for `desc table column`.
- Flag int // Some flag parsed from sql, such as FULL.
- Full bool
- User *auth.UserIdentity // Used for show grants.
+ Tp ast.ShowStmtType // Databases/Tables/Columns/....
+ DBName string
+ Table *ast.TableName // Used for showing columns.
+ Column *ast.ColumnName // Used for `desc table column`.
+ Flag int // Some flag parsed from sql, such as FULL.
+ Full bool
+ User *auth.UserIdentity // Used for show grants.
+ IfNotExists bool // Used for `show create database if not exists`
 
  Conditions []expression.Expression
 

planner/core/planbuilder.go

@@ -914,6 +914,7 @@ func (b *PlanBuilder) buildShow(show *ast.ShowStmt) (Plan, error) {
  Flag: show.Flag,
  Full: show.Full,
  User: show.User,
+ IfNotExists: show.IfNotExists,
  GlobalScope: show.GlobalScope,
  }.Init(b.ctx)
  switch showTp := show.Tp; showTp {