Snowflake: Support CREATE VIEW myview IF NOT EXISTS (apache#1961)

Author: etgarperets

src/ast/mod.rs

@@ -3284,6 +3284,17 @@ pub enum Statement {
         materialized: bool,
         /// View name
         name: ObjectName,
+        /// If `if_not_exists` is true, this flag is set to true if the view name comes before the `IF NOT EXISTS` clause.
+        /// Example:
+        /// ```sql
+        /// CREATE VIEW myview IF NOT EXISTS AS SELECT 1`
+        ///  ```
+        /// Otherwise, the flag is set to false if the view name comes after the clause
+        /// Example:
+        /// ```sql
+        /// CREATE VIEW IF NOT EXISTS myview AS SELECT 1`
+        ///  ```
+        name_before_not_exists: bool,
         columns: Vec<ViewColumnDef>,
         query: Box<Query>,
         options: CreateTableOptions,
@@ -5023,6 +5034,7 @@ impl fmt::Display for Statement {
                 temporary,
                 to,
                 params,
+                name_before_not_exists,
             } => {
                 write!(
                     f,
@@ -5035,11 +5047,18 @@ impl fmt::Display for Statement {
                 }
                 write!(
                     f,
-                    "{materialized}{temporary}VIEW {if_not_exists}{name}{to}",
+                    "{materialized}{temporary}VIEW {if_not_and_name}{to}",
+                    if_not_and_name = if *if_not_exists {
+                        if *name_before_not_exists {
+                            format!("{name} IF NOT EXISTS")
+                        } else {
+                            format!("IF NOT EXISTS {name}")
+                        }
+                    } else {
+                        format!("{name}")
+                    },
                     materialized = if *materialized { "MATERIALIZED " } else { "" },
-                    name = name,
                     temporary = if *temporary { "TEMPORARY " } else { "" },
-                    if_not_exists = if *if_not_exists { "IF NOT EXISTS " } else { "" },
                     to = to
                         .as_ref()
                         .map(|to| format!(" TO {to}"))

src/ast/spans.rs

@@ -400,6 +400,7 @@ impl Spanned for Statement {
                 if_not_exists: _,
                 temporary: _,
                 to,
+                name_before_not_exists: _,
                 params: _,
             } => union_spans(
                 core::iter::once(name.span())

src/parser/mod.rs

@@ -5849,12 +5849,17 @@ impl<'a> Parser<'a> {
     ) -> Result<Statement, ParserError> {
         let materialized = self.parse_keyword(Keyword::MATERIALIZED);
         self.expect_keyword_is(Keyword::VIEW)?;
-        let if_not_exists = dialect_of!(self is BigQueryDialect|SQLiteDialect|GenericDialect)
+        let allow_unquoted_hyphen = dialect_of!(self is BigQueryDialect);
+        // Tries to parse IF NOT EXISTS either before name or after name
+        // Name before IF NOT EXISTS is supported by snowflake but undocumented
+        let if_not_exists_first =
+            self.parse_keywords(&[Keyword::IF, Keyword::NOT, Keyword::EXISTS]);
+        let name = self.parse_object_name(allow_unquoted_hyphen)?;
+        let name_before_not_exists = !if_not_exists_first
             && self.parse_keywords(&[Keyword::IF, Keyword::NOT, Keyword::EXISTS]);
+        let if_not_exists = if_not_exists_first || name_before_not_exists;
         // Many dialects support `OR ALTER` right after `CREATE`, but we don't (yet).
         // ANSI SQL and Postgres support RECURSIVE here, but we don't support it either.
-        let allow_unquoted_hyphen = dialect_of!(self is BigQueryDialect);
-        let name = self.parse_object_name(allow_unquoted_hyphen)?;
         let columns = self.parse_view_columns()?;
         let mut options = CreateTableOptions::None;
         let with_options = self.parse_options(Keyword::WITH)?;
@@ -5921,6 +5926,7 @@ impl<'a> Parser<'a> {
             temporary,
             to,
             params: create_view_params,
+            name_before_not_exists,
         })
     }
 

tests/sqlparser_common.rs

@@ -8059,6 +8059,7 @@ fn parse_create_view() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("myschema.myview", name.to_string());
@@ -8127,6 +8128,7 @@ fn parse_create_view_with_columns() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("v", name.to_string());
@@ -8176,6 +8178,7 @@ fn parse_create_view_temporary() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("myschema.myview", name.to_string());
@@ -8215,6 +8218,7 @@ fn parse_create_or_replace_view() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("v", name.to_string());
@@ -8258,6 +8262,7 @@ fn parse_create_or_replace_materialized_view() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("v", name.to_string());
@@ -8297,6 +8302,7 @@ fn parse_create_materialized_view() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("myschema.myview", name.to_string());
@@ -8336,6 +8342,7 @@ fn parse_create_materialized_view_with_cluster_by() {
             temporary,
             to,
             params,
+            name_before_not_exists: _,
         } => {
             assert_eq!(or_alter, false);
             assert_eq!("myschema.myview", name.to_string());
@@ -16453,3 +16460,20 @@ fn parse_drop_stream() {
     }
     verified_stmt("DROP STREAM IF EXISTS s1");
 }
+
+#[test]
+fn parse_create_view_if_not_exists() {
+    // Name after IF NOT EXISTS
+    let sql: &'static str = "CREATE VIEW IF NOT EXISTS v AS SELECT 1";
+    let _ = all_dialects().verified_stmt(sql);
+    // Name before IF NOT EXISTS
+    let sql = "CREATE VIEW v IF NOT EXISTS AS SELECT 1";
+    let _ = all_dialects().verified_stmt(sql);
+    // Name missing from query
+    let sql = "CREATE VIEW IF NOT EXISTS AS SELECT 1";
+    let res = all_dialects().parse_sql_statements(sql);
+    assert_eq!(
+        ParserError::ParserError("Expected: AS, found: SELECT".to_string()),
+        res.unwrap_err()
+    );
+}