Fix: Date math with Interval keyword (#12082)

* feat: add failing parsing test and fix parser

Signed-off-by: Manan Gupta <manan@planetscale.com>

* test: add e2e tests for interval with math functions

Signed-off-by: Manan Gupta <manan@planetscale.com>

* test: explictly set the time-zone to prevent failures in CI

Signed-off-by: Manan Gupta <manan@planetscale.com>

Signed-off-by: Manan Gupta <manan@planetscale.com>

go/test/endtoend/vtgate/queries/misc/misc_test.go

@@ -161,3 +161,15 @@ func TestQueryTimeoutWithTables(t *testing.T) {
 	assert.Contains(t, err.Error(), "context deadline exceeded")
 	assert.Contains(t, err.Error(), "(errno 1317) (sqlstate 70100)")
 }
+
+// TestIntervalWithMathFunctions tests that the Interval keyword can be used with math functions.
+func TestIntervalWithMathFunctions(t *testing.T) {
+	mcmp, closer := start(t)
+	defer closer()
+
+	// Set the time zone explicitly to UTC, otherwise the output of FROM_UNIXTIME is going to be dependent
+	// on the time zone of the system.
+	mcmp.Exec("SET time_zone = '+00:00'")
+	mcmp.AssertMatches("select '2020-01-01' + interval month(DATE_SUB(FROM_UNIXTIME(1234), interval 1 month))-1 month", `[[CHAR("2020-12-01")]]`)
+	mcmp.AssertMatches("select DATE_ADD(MIN(FROM_UNIXTIME(1673444922)),interval -DAYOFWEEK(MIN(FROM_UNIXTIME(1673444922)))+1 DAY)", `[[DATETIME("2023-01-08 13:48:42")]]`)
+}

go/vt/sqlparser/parse_test.go

@@ -850,6 +850,12 @@ var (
 	}, {
 		input:  "select /* TIMESTAMPDIFF */ TIMESTAMPDIFF(MINUTE, '2008-01-02', '2008-01-04') from t",
 		output: "select /* TIMESTAMPDIFF */ timestampdiff(MINUTE, '2008-01-02', '2008-01-04') from t",
+	}, {
+		input:  "select DATE_ADD(MIN(FROM_UNIXTIME(1673444922)),interval -DAYOFWEEK(MIN(FROM_UNIXTIME(1673444922)))+1 DAY)",
+		output: "select DATE_ADD(min(FROM_UNIXTIME(1673444922)), interval (-DAYOFWEEK(min(FROM_UNIXTIME(1673444922))) + 1) DAY) from dual",
+	}, {
+		input:  "select '2020-01-01' + interval month(DATE_SUB(FROM_UNIXTIME(1234), interval 1 month))-1 month",
+		output: "select '2020-01-01' + interval (month(DATE_SUB(FROM_UNIXTIME(1234), interval 1 month)) - 1) month from dual",
 	}, {
 		input: "select /* dual */ 1 from dual",
 	}, {