feat: Omit table name when only one ident in SELECT

prql-compiler/src/ir/mod.rs

@@ -1,10 +1,12 @@
 mod expr;
 mod id_gen;
 mod ir_fold;
+mod table_counter;
 
 pub use expr::{Expr, ExprKind, UnOp};
 pub use id_gen::IdGenerator;
 pub use ir_fold::*;
+pub use table_counter::TableCounter;
 
 use serde::{Deserialize, Serialize};
 

prql-compiler/src/ir/table_counter.rs

@@ -0,0 +1,27 @@
+use std::collections::HashSet;
+
+use super::{IrFold, TId, Transform};
+
+/// Folder that counts the number of table referenced in a PRQL query.
+#[derive(Debug, Default)]
+pub struct TableCounter {
+    tables: HashSet<TId>,
+}
+
+impl TableCounter {
+    pub fn count(&self) -> usize {
+        self.tables.len()
+    }
+}
+
+impl IrFold for TableCounter {
+    fn fold_transforms(&mut self, transforms: Vec<Transform>) -> anyhow::Result<Vec<Transform>> {
+        for transform in &transforms {
+            if let Transform::Join { with: tid, .. } | Transform::From(tid) = transform {
+                self.tables.insert(*tid);
+            }
+        }
+
+        Ok(transforms)
+    }
+}

prql-compiler/src/lib.rs

@@ -225,7 +225,6 @@ mod test {
     }
 
     #[test]
-    #[ignore]
     fn test_quoting() {
         // GH-#822
         assert_display_snapshot!((compile(r###"
@@ -238,7 +237,7 @@ join some_schema.tablename [~id]
         "###).unwrap()), @r###"
         WITH "UPPER" AS (
           SELECT
-            lower.*
+            *
           FROM
             lower
         )
@@ -287,7 +286,7 @@ select `first name`
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          invoices.*
+          *
         FROM
           invoices
         ORDER BY
@@ -298,7 +297,6 @@ select `first name`
     }
 
     #[test]
-    #[ignore]
     fn test_ranges() {
         let query = r###"
         from employees
@@ -307,7 +305,7 @@ select `first name`
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         WHERE
@@ -329,7 +327,7 @@ select `first name`
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          events.*
+          *
         FROM
           events
         WHERE
@@ -339,7 +337,6 @@ select `first name`
     }
 
     #[test]
-    #[ignore]
     fn test_interval() {
         let query = r###"
         from projects
@@ -348,7 +345,7 @@ select `first name`
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          projects.*,
+          *,
           start + INTERVAL 10 DAY AS first_check_in
         FROM
           projects
@@ -367,7 +364,7 @@ select `first name`
         ]
         "###).unwrap()), @r###"
         SELECT
-          to_do_empty_table.*,
+          *,
           DATE '2011-02-01' AS date,
           TIMESTAMP '2011-02-01T10:00' AS timestamp,
           TIME '14:00' AS time
@@ -642,7 +639,6 @@ select `first name`
     }
 
     #[test]
-    #[ignore]
     fn test_filter() {
         // https://github.com/prql/prql/issues/469
         let query = r###"
@@ -657,7 +653,7 @@ select `first name`
         filter age > 25 and age < 40
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         WHERE
@@ -671,7 +667,7 @@ select `first name`
         filter age < 40
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         WHERE
@@ -681,7 +677,6 @@ select `first name`
     }
 
     #[test]
-    #[ignore]
     fn test_nulls() {
         assert_display_snapshot!((compile(r###"
         from employees
@@ -699,7 +694,7 @@ select `first name`
         derive amount = amount + 2 ?? 3 * 5
         "###).unwrap()), @r###"
         SELECT
-          employees.*,
+          *,
           COALESCE(amount + 2, 3 * 5) AS amount
         FROM
           employees
@@ -711,7 +706,7 @@ select `first name`
         filter first_name == null and null == last_name
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         WHERE
@@ -725,7 +720,7 @@ select `first name`
         filter first_name != null and null != last_name
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         WHERE
@@ -742,7 +737,7 @@ select `first name`
         take ..10
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         LIMIT
@@ -754,7 +749,7 @@ select `first name`
         take 5..10
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         LIMIT
@@ -766,7 +761,7 @@ select `first name`
         take 5..
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees OFFSET 4
         "###);
@@ -776,7 +771,7 @@ select `first name`
         take 5..5
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         LIMIT
@@ -790,7 +785,7 @@ select `first name`
         take 1..5
         "###).unwrap()), @r###"
         SELECT
-          employees.*
+          *
         FROM
           employees
         LIMIT
@@ -1434,15 +1429,14 @@ take 20
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          github_json.*,
-          github_json.`event.type` AS event_type_dotted
+          *,
+          `event.type` AS event_type_dotted
         FROM
           github_json
         "###);
     }
 
     #[test]
-    #[ignore]
     fn test_ident_escaping() {
         // Generic
         let query = r###"
@@ -1452,7 +1446,7 @@ take 20
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          "anim""ls".*,
+          *,
           "BeeName" AS "čebela",
           "bear's_name" AS medved
         FROM
@@ -1469,7 +1463,7 @@ take 20
 
         assert_display_snapshot!((compile(query).unwrap()), @r###"
         SELECT
-          `anim"ls`.*,
+          *,
           `BeeName` AS `čebela`,
           `bear's_name` AS medved
         FROM
@@ -1488,7 +1482,7 @@ take 20
         assert_display_snapshot!(sql,
             @r###"
         SELECT
-          employees.*,
+          *,
           true AS always_true
         FROM
           employees

prql-compiler/src/sql/codegen.rs

@@ -414,14 +414,17 @@ pub(super) fn translate_ident(
     context: &Context,
 ) -> Vec<sql_ast::Ident> {
     let mut parts = Vec::with_capacity(4);
-    if let Some(relation) = relation_name {
-        // Special-case this for BigQuery, Ref #852
-        if matches!(context.dialect.dialect(), Dialect::BigQuery) {
-            parts.push(relation);
-        } else {
-            parts.extend(relation.split('.').map(|s| s.to_string()));
+    if !context.omit_ident_prefix || column.is_none() {
+        if let Some(relation) = relation_name {
+            // Special-case this for BigQuery, Ref #852
+            if matches!(context.dialect.dialect(), Dialect::BigQuery) {
+                parts.push(relation);
+            } else {
+                parts.extend(relation.split('.').map(|s| s.to_string()));
+            }
         }
     }
+
     parts.extend(column);
 
     parts

prql-compiler/src/sql/translator.rs

@@ -15,14 +15,15 @@ use sqlparser::ast::{self as sql_ast, Select, SetExpr, TableWithJoins};
 use std::collections::HashMap;
 
 use crate::ast::{DialectHandler, Literal};
-use crate::ir::{Expr, ExprKind, Query, Table, TableExpr, Transform};
+use crate::ir::{Expr, ExprKind, IrFold, Query, Table, TableCounter, TableExpr, Transform};
 
 use super::anchor::AnchorContext;
 use super::codegen::*;
 
 pub(super) struct Context {
     pub dialect: Box<dyn DialectHandler>,
     pub anchor: AnchorContext,
+    pub omit_ident_prefix: bool,
 }
 
 /// Translate a PRQL AST into a SQL string.
@@ -50,7 +51,11 @@ pub fn translate_query(query: Query) -> Result<sql_ast::Query> {
 
     let (anchor, query) = AnchorContext::of(query);
 
-    let mut context = Context { dialect, anchor };
+    let mut context = Context {
+        dialect,
+        anchor,
+        omit_ident_prefix: false,
+    };
 
     // extract tables and the pipeline
     let tables = into_tables(query.expr, query.tables, &mut context)?;
@@ -121,6 +126,10 @@ fn sql_query_of_atomic_query(
     pipeline: Vec<Transform>,
     context: &mut Context,
 ) -> Result<sql_ast::Query> {
+    let mut counter = TableCounter::default();
+    let pipeline = counter.fold_transforms(pipeline)?;
+    context.omit_ident_prefix = counter.count() == 1;
+
     let select = context.anchor.determine_select_columns(&pipeline);
 
     let mut from = pipeline
@@ -372,6 +381,7 @@ mod test {
         let mut context = Context {
             dialect: Box::new(GenericDialect {}),
             anchor,
+            omit_ident_prefix: false,
         };
 
         let table = Table {

prql-python/src/lib.rs

@@ -33,7 +33,7 @@ mod test {
     fn parse_for_python() -> Result<()> {
         assert_eq!(
             to_sql("from employees | filter (age | in 20..30)")?,
-            "SELECT\n  employees.*\nFROM\n  employees\nWHERE\n  employees.age BETWEEN 20\n  AND 30"
+            "SELECT\n  *\nFROM\n  employees\nWHERE\n  age BETWEEN 20\n  AND 30"
         );
 
         Ok(())