fix: Normalize default constrain fn name (#2737)

* fix: normalize current_timestamp to current_timestamp()

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* add sqlness case

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

* fix clippy lints

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

---------

Signed-off-by: Ruihang Xia <waynestxia@gmail.com>

src/datatypes/src/schema.rs

@@ -13,7 +13,7 @@
 // limitations under the License.
 
 mod column_schema;
-mod constraint;
+pub mod constraint;
 mod raw;
 
 use std::collections::HashMap;

src/datatypes/src/schema/constraint.rs

@@ -24,9 +24,9 @@ use crate::value::Value;
 use crate::vectors::operations::VectorOp;
 use crate::vectors::{TimestampMillisecondVector, VectorRef};
 
-const CURRENT_TIMESTAMP: &str = "current_timestamp";
-const CURRENT_TIMESTAMP_FN: &str = "current_timestamp()";
-const NOW_FN: &str = "now()";
+pub const CURRENT_TIMESTAMP: &str = "current_timestamp";
+pub const CURRENT_TIMESTAMP_FN: &str = "current_timestamp()";
+pub const NOW_FN: &str = "now()";
 
 /// Column's default constraint.
 #[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]

src/sql/src/error.rs

@@ -63,6 +63,7 @@ pub enum Error {
     Syntax {
         #[snafu(source)]
         error: ParserError,
+        location: Location,
     },
 
     #[snafu(display("Missing time index constraint"))]

src/sql/src/statements.rs

@@ -37,6 +37,7 @@ use common_base::bytes::Bytes;
 use common_query::AddColumnLocation;
 use common_time::Timestamp;
 use datatypes::prelude::ConcreteDataType;
+use datatypes::schema::constraint::{CURRENT_TIMESTAMP, CURRENT_TIMESTAMP_FN};
 use datatypes::schema::{ColumnDefaultConstraint, ColumnSchema, COMMENT_KEY};
 use datatypes::types::cast::CastOption;
 use datatypes::types::{cast, TimestampType};
@@ -270,8 +271,13 @@ fn parse_column_default_constraint(
                 ColumnDefaultConstraint::Value(sql_value_to_value(column_name, data_type, v)?)
             }
             ColumnOption::Default(Expr::Function(func)) => {
+                let mut func = format!("{func}").to_lowercase();
+                // normalize CURRENT_TIMESTAMP to CURRENT_TIMESTAMP()
+                if func == CURRENT_TIMESTAMP {
+                    func = CURRENT_TIMESTAMP_FN.to_string();
+                }
                 // Always use lowercase for function expression
-                ColumnDefaultConstraint::Function(format!("{func}").to_lowercase())
+                ColumnDefaultConstraint::Function(func.to_lowercase())
             }
             ColumnOption::Default(expr) => {
                 return UnsupportedDefaultValueSnafu {