Support Snowflake/BigQuery TRIM. (#975)

tests/sqlparser_snowflake.rs

@@ -1039,3 +1039,28 @@ fn test_snowflake_stage_object_names() {
         }
     }
 }
+
+#[test]
+fn test_snowflake_trim() {
+    let real_sql = r#"SELECT customer_id, TRIM(sub_items.value:item_price_id, '"', "a") AS item_price_id FROM models_staging.subscriptions"#;
+    assert_eq!(snowflake().verified_stmt(real_sql).to_string(), real_sql);
+
+    let sql_only_select = "SELECT TRIM('xyz', 'a')";
+    let select = snowflake().verified_only_select(sql_only_select);
+    assert_eq!(
+        &Expr::Trim {
+            expr: Box::new(Expr::Value(Value::SingleQuotedString("xyz".to_owned()))),
+            trim_where: None,
+            trim_what: None,
+            trim_characters: Some(vec![Expr::Value(Value::SingleQuotedString("a".to_owned()))]),
+        },
+        expr_from_projection(only(&select.projection))
+    );
+
+    // missing comma separation
+    let error_sql = "SELECT TRIM('xyz' 'a')";
+    assert_eq!(
+        ParserError::ParserError("Expected ), found: 'a'".to_owned()),
+        snowflake().parse_sql_statements(error_sql).unwrap_err()
+    );
+}