feat: improve error message for typo in IF NOT EXISTS (#3817)

* refactor: improve error message for typo in IF NOT EXISTS

Signed-off-by: tison <wander4096@gmail.com>

* support table name 'if'

Signed-off-by: tison <wander4096@gmail.com>

* add sqlness cases

Signed-off-by: tison <wander4096@gmail.com>

---------

Signed-off-by: tison <wander4096@gmail.com>

src/sql/src/parsers/create_parser.rs

@@ -28,7 +28,7 @@ use table::requests::validate_table_option;
 use crate::ast::{ColumnDef, Ident, TableConstraint};
 use crate::error::{
     self, InvalidColumnOptionSnafu, InvalidTableOptionSnafu, InvalidTimeIndexSnafu,
-    MissingTimeIndexSnafu, Result, SyntaxSnafu,
+    MissingTimeIndexSnafu, Result, SyntaxSnafu, UnexpectedSnafu, UnsupportedSnafu,
 };
 use crate::parser::ParserContext;
 use crate::statements::create::{
@@ -63,9 +63,7 @@ impl<'a> ParserContext<'a> {
         self.parser
             .expect_keyword(Keyword::TABLE)
             .context(SyntaxSnafu)?;
-        let if_not_exists =
-            self.parser
-                .parse_keywords(&[Keyword::IF, Keyword::NOT, Keyword::EXISTS]);
+        let if_not_exists = self.parse_if_not_exist()?;
         let table_name = self.intern_parse_table_name()?;
         let (columns, constraints) = self.parse_columns()?;
         if !columns.is_empty() {
@@ -86,11 +84,7 @@ impl<'a> ParserContext<'a> {
 
     fn parse_create_database(&mut self) -> Result<Statement> {
         let _ = self.parser.next_token();
-
-        let if_not_exists =
-            self.parser
-                .parse_keywords(&[Keyword::IF, Keyword::NOT, Keyword::EXISTS]);
-
+        let if_not_exists = self.parse_if_not_exist()?;
         let database_name = self.parse_object_name().context(error::UnexpectedSnafu {
             sql: self.sql,
             expected: "a database name",
@@ -105,9 +99,8 @@ impl<'a> ParserContext<'a> {
 
     fn parse_create_table(&mut self) -> Result<Statement> {
         let _ = self.parser.next_token();
-        let if_not_exists =
-            self.parser
-                .parse_keywords(&[Keyword::IF, Keyword::NOT, Keyword::EXISTS]);
+
+        let if_not_exists = self.parse_if_not_exist()?;
 
         let table_name = self.intern_parse_table_name()?;
 
@@ -144,6 +137,35 @@ impl<'a> ParserContext<'a> {
         Ok(Statement::CreateTable(create_table))
     }
 
+    fn parse_if_not_exist(&mut self) -> Result<bool> {
+        match self.parser.peek_token().token {
+            Token::Word(w) if Keyword::IF != w.keyword => return Ok(false),
+            _ => {}
+        }
+
+        if self.parser.parse_keywords(&[Keyword::IF, Keyword::NOT]) {
+            return self
+                .parser
+                .expect_keyword(Keyword::EXISTS)
+                .map(|_| true)
+                .context(UnexpectedSnafu {
+                    sql: self.sql,
+                    expected: "EXISTS",
+                    actual: self.peek_token_as_string(),
+                });
+        }
+
+        if self.parser.parse_keywords(&[Keyword::IF, Keyword::EXISTS]) {
+            return UnsupportedSnafu {
+                sql: self.sql,
+                keyword: "EXISTS",
+            }
+            .fail();
+        }
+
+        Ok(false)
+    }
+
     fn parse_create_table_options(&mut self) -> Result<OptionMap> {
         let options = self
             .parser

tests/cases/standalone/common/create/create_if_not_exists.result

@@ -0,0 +1,40 @@
+CREATE TABLE IF NOT EXIST t();
+
+Error: 2000(InvalidSyntax), Unexpected token while parsing SQL statement: CREATE TABLE IF NOT EXIST t();, expected: 'EXISTS', found: EXIST: sql parser error: Expected EXISTS, found: EXIST at Line: 1, Column 21
+
+CREATE TABLE IF NOT t();
+
+Error: 2000(InvalidSyntax), Unexpected token while parsing SQL statement: CREATE TABLE IF NOT t();, expected: 'EXISTS', found: t: sql parser error: Expected EXISTS, found: t at Line: 1, Column 21
+
+CREATE TABLE IF EXISTS t();
+
+Error: 1001(Unsupported), SQL statement is not supported: CREATE TABLE IF EXISTS t();, keyword: EXISTS
+
+CREATE TABLE IF NOT EXISTS t();
+
+Error: 2000(InvalidSyntax), Missing time index constraint
+
+CREATE TABLE t();
+
+Error: 2000(InvalidSyntax), Missing time index constraint
+
+CREATE TABLE t(ts TIMESTAMP TIME INDEX);
+
+Affected Rows: 0
+
+CREATE TABLE IF();
+
+Error: 2000(InvalidSyntax), Missing time index constraint
+
+CREATE TABLE IF(ts TIMESTAMP TIME INDEX);
+
+Affected Rows: 0
+
+DROP TABLE t;
+
+Affected Rows: 0
+
+DROP TABLE IF;
+
+Affected Rows: 0
+

tests/cases/standalone/common/create/create_if_not_exists.sql

@@ -0,0 +1,19 @@
+CREATE TABLE IF NOT EXIST t();
+
+CREATE TABLE IF NOT t();
+
+CREATE TABLE IF EXISTS t();
+
+CREATE TABLE IF NOT EXISTS t();
+
+CREATE TABLE t();
+
+CREATE TABLE t(ts TIMESTAMP TIME INDEX);
+
+CREATE TABLE IF();
+
+CREATE TABLE IF(ts TIMESTAMP TIME INDEX);
+
+DROP TABLE t;
+
+DROP TABLE IF;