feat: issue #8969 adding position function (#8988)

* feat: issue #8969 adding position function

* reuse Instr

datafusion/expr/src/built_in_function.rs

@@ -1463,7 +1463,7 @@ impl BuiltinScalarFunction {
             BuiltinScalarFunction::Chr => &["chr"],
             BuiltinScalarFunction::EndsWith => &["ends_with"],
             BuiltinScalarFunction::InitCap => &["initcap"],
-            BuiltinScalarFunction::InStr => &["instr"],
+            BuiltinScalarFunction::InStr => &["instr", "position"],
             BuiltinScalarFunction::Left => &["left"],
             BuiltinScalarFunction::Lower => &["lower"],
             BuiltinScalarFunction::Lpad => &["lpad"],

datafusion/sql/src/expr/mod.rs

@@ -514,7 +514,9 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
             SQLExpr::Struct { values, fields } => {
                 self.parse_struct(values, fields, schema, planner_context)
             }
-
+            SQLExpr::Position { expr, r#in } => {
+                self.sql_position_to_expr(*expr, *r#in, schema, planner_context)
+            }
             _ => not_impl_err!("Unsupported ast node in sqltorel: {sql:?}"),
         }
     }
@@ -704,7 +706,20 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
         };
         Ok(Expr::ScalarFunction(ScalarFunction::new(fun, args)))
     }
-
+    fn sql_position_to_expr(
+        &self,
+        substr_expr: SQLExpr,
+        str_expr: SQLExpr,
+        schema: &DFSchema,
+        planner_context: &mut PlannerContext,
+    ) -> Result<Expr> {
+        let fun = BuiltinScalarFunction::InStr;
+        let substr =
+            self.sql_expr_to_logical_expr(substr_expr, schema, planner_context)?;
+        let fullstr = self.sql_expr_to_logical_expr(str_expr, schema, planner_context)?;
+        let args = vec![fullstr, substr];
+        Ok(Expr::ScalarFunction(ScalarFunction::new(fun, args)))
+    }
     fn sql_agg_with_filter_to_expr(
         &self,
         expr: SQLExpr,

datafusion/sqllogictest/test_files/position.slt

@@ -0,0 +1,43 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+
+#   http://www.apache.org/licenses/LICENSE-2.0
+
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+# test position in select
+query I
+select position('world' in 'hello world');
+----
+7
+
+
+
+# test in expression
+query I
+select 1000 where position('world' in 'hello world') != 100;
+----
+1000
+
+
+# test in expression
+query I
+select 100000 where position('legend' in 'league of legend') = 11;
+----
+100000
+
+
+# test in expression
+query I
+select 100000 where position('legend' in 'league of legend') != 11;
+----

docs/source/user-guide/sql/scalar_functions.md

@@ -641,6 +641,7 @@ nullif(expression1, expression2)
 - [levenshtein](#levenshtein)
 - [substr_index](#substr_index)
 - [find_in_set](#find_in_set)
+- [position](#position)
 
 ### `ascii`
 
@@ -1300,6 +1301,19 @@ regexp_replace(str, regexp, replacement, flags)
   - **g**: (global) Search globally and don't return after the first match.
   - **i**: (insensitive) Ignore case when matching.
 
+### `position`
+
+Returns the position of substr in orig_str
+
+```
+position(substr in origstr)
+```
+
+#### Arguments
+
+- **substr**: he pattern string.
+- **origstr**: The model string.
+
 ## Time and Date Functions
 
 - [now](#now)