DuckDB, Postgres, SQLite: NOT NULL and NOTNULL expressions

src/dialect/duckdb.rs

@@ -15,7 +15,7 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use crate::dialect::Dialect;
+use crate::dialect::{Dialect, IsNotNullAlias};
 
 /// A [`Dialect`] for [DuckDB](https://duckdb.org/)
 #[derive(Debug, Default)]
@@ -94,4 +94,13 @@ impl Dialect for DuckDbDialect {
     fn supports_order_by_all(&self) -> bool {
         true
     }
+
+    /// DuckDB supports `NOT NULL` and `NOTNULL` as aliases
+    /// for `IS NOT NULL`, see DuckDB Comparisons <https://duckdb.org/docs/stable/sql/expressions/comparison_operators#between-and-is-not-null>
+    fn supports_is_not_null_alias(&self, alias: IsNotNullAlias) -> bool {
+        match alias {
+            IsNotNullAlias::NotNull => true,
+            IsNotNullAlias::NotSpaceNull => true,
+        }
+    }
 }

src/dialect/mod.rs

@@ -55,6 +55,7 @@ use crate::keywords::Keyword;
 use crate::parser::{Parser, ParserError};
 use crate::tokenizer::Token;
 
+use crate::dialect::IsNotNullAlias::{NotNull, NotSpaceNull};
 #[cfg(not(feature = "std"))]
 use alloc::boxed::Box;
 
@@ -650,8 +651,19 @@ pub trait Dialect: Debug + Any {
                 Token::Word(w) if w.keyword == Keyword::MATCH => Ok(p!(Like)),
                 Token::Word(w) if w.keyword == Keyword::SIMILAR => Ok(p!(Like)),
                 Token::Word(w) if w.keyword == Keyword::MEMBER => Ok(p!(Like)),
+                Token::Word(w)
+                    if w.keyword == Keyword::NULL
+                        && self.supports_is_not_null_alias(NotSpaceNull) =>
+                {
+                    Ok(p!(Is))
+                }
                 _ => Ok(self.prec_unknown()),
             },
+            Token::Word(w)
+                if w.keyword == Keyword::NOTNULL && self.supports_is_not_null_alias(NotNull) =>
+            {
+                Ok(p!(Is))
+            }
             Token::Word(w) if w.keyword == Keyword::IS => Ok(p!(Is)),
             Token::Word(w) if w.keyword == Keyword::IN => Ok(p!(Between)),
             Token::Word(w) if w.keyword == Keyword::BETWEEN => Ok(p!(Between)),
@@ -1076,6 +1088,15 @@ pub trait Dialect: Debug + Any {
     fn supports_comma_separated_drop_column_list(&self) -> bool {
         false
     }
+
+    /// Returns true if the dialect supports the passed in alias.
+    /// See [IsNotNullAlias].
+    fn supports_is_not_null_alias(&self, alias: IsNotNullAlias) -> bool {
+        match alias {
+            NotNull => false,
+            NotSpaceNull => false,
+        }
+    }
 }
 
 /// This represents the operators for which precedence must be defined
@@ -1102,6 +1123,13 @@ pub enum Precedence {
     Or,
 }
 
+/// Possible aliases for `IS NOT NULL` supported
+/// by some non-standard dialects.
+pub enum IsNotNullAlias {
+    NotNull,
+    NotSpaceNull,
+}
+
 impl dyn Dialect {
     #[inline]
     pub fn is<T: Dialect>(&self) -> bool {

src/dialect/postgresql.rs

@@ -28,7 +28,7 @@
 // limitations under the License.
 use log::debug;
 
-use crate::dialect::{Dialect, Precedence};
+use crate::dialect::{Dialect, IsNotNullAlias, Precedence};
 use crate::keywords::Keyword;
 use crate::parser::{Parser, ParserError};
 use crate::tokenizer::Token;
@@ -262,4 +262,13 @@ impl Dialect for PostgreSqlDialect {
     fn supports_alter_column_type_using(&self) -> bool {
         true
     }
+
+    /// Postgres supports `NOTNULL` as an alias for `IS NOT NULL`
+    /// but does not support `NOT NULL`.  See: <https://www.postgresql.org/docs/17/functions-comparison.html>
+    fn supports_is_not_null_alias(&self, alias: IsNotNullAlias) -> bool {
+        match alias {
+            IsNotNullAlias::NotNull => true,
+            IsNotNullAlias::NotSpaceNull => false,
+        }
+    }
 }

src/dialect/sqlite.rs

@@ -20,7 +20,7 @@ use alloc::boxed::Box;
 
 use crate::ast::BinaryOperator;
 use crate::ast::{Expr, Statement};
-use crate::dialect::Dialect;
+use crate::dialect::{Dialect, IsNotNullAlias};
 use crate::keywords::Keyword;
 use crate::parser::{Parser, ParserError};
 
@@ -110,4 +110,13 @@ impl Dialect for SQLiteDialect {
     fn supports_dollar_placeholder(&self) -> bool {
         true
     }
+
+    /// SQLite supports ``NOT NULL` and `NOTNULL` as
+    /// aliases for `IS NOT NULL`, see: <https://sqlite.org/syntax/expr.html>
+    fn supports_is_not_null_alias(&self, alias: IsNotNullAlias) -> bool {
+        match alias {
+            IsNotNullAlias::NotNull => true,
+            IsNotNullAlias::NotSpaceNull => true,
+        }
+    }
 }

src/keywords.rs

@@ -608,6 +608,7 @@ define_keywords!(
     NOT,
     NOTHING,
     NOTIFY,
+    NOTNULL,
     NOWAIT,
     NO_WRITE_TO_BINLOG,
     NTH_VALUE,

src/parser/mod.rs

@@ -35,6 +35,7 @@ use IsOptional::*;
 use crate::ast::helpers::stmt_create_table::{CreateTableBuilder, CreateTableConfiguration};
 use crate::ast::Statement::CreatePolicy;
 use crate::ast::*;
+use crate::dialect::IsNotNullAlias::{NotNull, NotSpaceNull};
 use crate::dialect::*;
 use crate::keywords::{Keyword, ALL_KEYWORDS};
 use crate::tokenizer::*;
@@ -3562,6 +3563,7 @@ impl<'a> Parser<'a> {
                     let negated = self.parse_keyword(Keyword::NOT);
                     let regexp = self.parse_keyword(Keyword::REGEXP);
                     let rlike = self.parse_keyword(Keyword::RLIKE);
+                    let null = self.parse_keyword(Keyword::NULL);
                     if regexp || rlike {
                         Ok(Expr::RLike {
                             negated,
@@ -3571,6 +3573,8 @@ impl<'a> Parser<'a> {
                             ),
                             regexp,
                         })
+                    } else if dialect.supports_is_not_null_alias(NotSpaceNull) && negated && null {
+                        Ok(Expr::IsNotNull(Box::new(expr)))
                     } else if self.parse_keyword(Keyword::IN) {
                         self.parse_in(expr, negated)
                     } else if self.parse_keyword(Keyword::BETWEEN) {
@@ -3608,6 +3612,9 @@ impl<'a> Parser<'a> {
                         self.expected("IN or BETWEEN after NOT", self.peek_token())
                     }
                 }
+                Keyword::NOTNULL if dialect.supports_is_not_null_alias(NotNull) => {
+                    Ok(Expr::IsNotNull(Box::new(expr)))
+                }
                 Keyword::MEMBER => {
                     if self.parse_keyword(Keyword::OF) {
                         self.expect_token(&Token::LParen)?;

tests/sqlparser_common.rs

@@ -32,8 +32,8 @@ use sqlparser::ast::TableFactor::{Pivot, Unpivot};
 use sqlparser::ast::*;
 use sqlparser::dialect::{
     AnsiDialect, BigQueryDialect, ClickHouseDialect, DatabricksDialect, Dialect, DuckDbDialect,
-    GenericDialect, HiveDialect, MsSqlDialect, MySqlDialect, PostgreSqlDialect, RedshiftSqlDialect,
-    SQLiteDialect, SnowflakeDialect,
+    GenericDialect, HiveDialect, IsNotNullAlias, MsSqlDialect, MySqlDialect, PostgreSqlDialect,
+    RedshiftSqlDialect, SQLiteDialect, SnowflakeDialect,
 };
 use sqlparser::keywords::{Keyword, ALL_KEYWORDS};
 use sqlparser::parser::{Parser, ParserError, ParserOptions};
@@ -15974,3 +15974,79 @@ fn parse_create_procedure_with_parameter_modes() {
         _ => unreachable!(),
     }
 }
+
+#[test]
+fn parse_not_null_unsupported() {
+    // Only DuckDB and SQLite support `x NOT NULL` as an expression
+    // All other dialects fail to parse the `NOT NULL` portion
+    let dialects =
+        all_dialects_except(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotSpaceNull));
+    let _ = dialects.expr_parses_to("x NOT NULL", "x");
+}
+
+#[test]
+fn parse_not_null_supported() {
+    // DuckDB and SQLite support `x NOT NULL` as an alias for `x IS NOT NULL`
+    let dialects =
+        all_dialects_where(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotSpaceNull));
+    let _ = dialects.expr_parses_to("x NOT NULL", "x IS NOT NULL");
+}
+
+#[test]
+fn test_not_null_precedence() {
+    // For dialects which support it, `NOT NULL NOT NULL` should
+    // parse as `(NOT (NULL IS NOT NULL))`
+    let supported_dialects =
+        all_dialects_where(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotSpaceNull));
+    let unsuported_dialects =
+        all_dialects_except(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotSpaceNull));
+
+    assert_matches!(
+        supported_dialects.expr_parses_to("NOT NULL NOT NULL", "NOT NULL IS NOT NULL"),
+        Expr::UnaryOp {
+            op: UnaryOperator::Not,
+            ..
+        }
+    );
+
+    // for unsupported dialects, parsing should stop at `NOT NULL`
+    unsuported_dialects.expr_parses_to("NOT NULL NOT NULL", "NOT NULL");
+}
+
+#[test]
+fn parse_notnull_unsupported() {
+    // Only Postgres, DuckDB, and SQLite support `x NOTNULL` as an expression
+    // All other dialects consider `x NOTNULL` like `x AS NOTNULL` and thus
+    // consider `NOTNULL` an alias for x.
+    let dialects = all_dialects_except(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotNull));
+    let _ = dialects
+        .verified_only_select_with_canonical("SELECT NULL NOTNULL", "SELECT NULL AS NOTNULL");
+}
+
+#[test]
+fn parse_notnull_supported() {
+    // Postgres, DuckDB and SQLite support `x NOTNULL` as an alias for `x IS NOT NULL`
+    let dialects = all_dialects_where(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotNull));
+    let _ = dialects.expr_parses_to("x NOTNULL", "x IS NOT NULL");
+}
+
+#[test]
+fn test_notnull_precedence() {
+    // For dialects which support it, `NOT NULL NOTNULL` should
+    // parse as `(NOT (NULL IS NOT NULL))`
+    let supported_dialects =
+        all_dialects_where(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotNull));
+    let unsuported_dialects =
+        all_dialects_except(|d| d.supports_is_not_null_alias(IsNotNullAlias::NotNull));
+
+    assert_matches!(
+        supported_dialects.expr_parses_to("NOT NULL NOTNULL", "NOT NULL IS NOT NULL"),
+        Expr::UnaryOp {
+            op: UnaryOperator::Not,
+            ..
+        }
+    );
+
+    // for unsupported dialects, parsing should stop at `NOT NULL`
+    unsuported_dialects.expr_parses_to("NOT NULL NOTNULL", "NOT NULL");
+}