fix: proper postgres unit quotes (#4537)

Author: m-span

prqlc/prqlc/src/sql/dialect.rs

@@ -167,7 +167,7 @@ pub(super) trait DialectHandler: Any + Debug {
     }
 
     /// Whether or not intervals such as `INTERVAL 1 HOUR` require quotes like
-    /// `INTERVAL '1' HOUR`
+    /// `INTERVAL '1 HOUR'`
     fn requires_quotes_intervals(&self) -> bool {
         false
     }

prqlc/prqlc/src/sql/gen_expr.rs

@@ -399,20 +399,29 @@ pub(super) fn translate_literal(l: Literal, ctx: &Context) -> Result<sql_ast::Ex
                     )))
                 }
             };
-            let value = if ctx.dialect.requires_quotes_intervals() {
-                Box::new(sql_ast::Expr::Value(Value::SingleQuotedString(
-                    vau.n.to_string(),
-                )))
+            if ctx.dialect.requires_quotes_intervals() {
+                //postgres requires quotes around number and unit together eg '3 WEEK'
+                let value = Box::new(sql_ast::Expr::Value(Value::SingleQuotedString(format!(
+                    "{} {}",
+                    vau.n, sql_parser_datetime
+                ))));
+                sql_ast::Expr::Interval(sqlparser::ast::Interval {
+                    value,
+                    leading_field: None, //set to none since field is now contained in string
+                    leading_precision: None,
+                    last_field: None,
+                    fractional_seconds_precision: None,
+                })
             } else {
-                Box::new(translate_literal(Literal::Integer(vau.n), ctx)?)
-            };
-            sql_ast::Expr::Interval(sqlparser::ast::Interval {
-                value,
-                leading_field: Some(sql_parser_datetime),
-                leading_precision: None,
-                last_field: None,
-                fractional_seconds_precision: None,
-            })
+                let value = Box::new(translate_literal(Literal::Integer(vau.n), ctx)?);
+                sql_ast::Expr::Interval(sqlparser::ast::Interval {
+                    value,
+                    leading_field: Some(sql_parser_datetime),
+                    leading_precision: None,
+                    last_field: None,
+                    fractional_seconds_precision: None,
+                })
+            }
         }
     })
 }

prqlc/prqlc/tests/integration/sql.rs

@@ -1265,7 +1265,21 @@ fn test_interval() {
     assert_snapshot!((compile(query).unwrap()), @r###"
     SELECT
       *,
-      "start" + INTERVAL '10' DAY AS first_check_in
+      "start" + INTERVAL '10 DAY' AS first_check_in
+    FROM
+      projects
+    "###);
+
+    let query = r###"
+    prql target:sql.glaredb
+
+    from projects
+    derive first_check_in = start + 10days
+    "###;
+    assert_snapshot!((compile(query).unwrap()), @r###"
+    SELECT
+      *,
+      "start" + INTERVAL '10 DAY' AS first_check_in
     FROM
       projects
     "###);