parser: support show create database if not exists syntax (#148)

See: https://dev.mysql.com/doc/refman/5.7/en/show-create-database.html
pingcap · Jan 3, 2019 · 5d5a6dd · 5d5a6dd
1 parent 989b499
commit 5d5a6dd
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diff --git a/ast/dml.go b/ast/dml.go
@@ -1317,13 +1317,14 @@ type ShowStmt struct {
 	dmlNode
 	resultSetNode
 
-	Tp     ShowStmtType // Databases/Tables/Columns/....
-	DBName string
-	Table  *TableName  // Used for showing columns.
-	Column *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          ShowStmtType // Databases/Tables/Columns/....
+	DBName      string
+	Table       *TableName  // Used for showing columns.
+	Column      *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