From 5175443c76ef38337a423e8bba22c75480f59bf8 Mon Sep 17 00:00:00 2001
From: Fedomn <fedomn.ma@gmail.com>
Date: Fri, 7 Oct 2022 11:11:08 +0800
Subject: [PATCH] feat(alias): support alias table

Signed-off-by: Fedomn <fedomn.ma@gmail.com>
---
 src/binder/expression/mod.rs |  6 +++++-
 src/binder/table/mod.rs      | 21 +++++++++++++++------
 tests/slt/alias.slt          | 26 ++++++++++++++++++++++++++
 3 files changed, 46 insertions(+), 7 deletions(-)

diff --git a/src/binder/expression/mod.rs b/src/binder/expression/mod.rs
index d68102c..9dc9741 100644
--- a/src/binder/expression/mod.rs
+++ b/src/binder/expression/mod.rs
@@ -142,7 +142,11 @@ impl Binder {
 
         if let Some(table) = table_name {
             // handle table.col syntax
-            let table_catalog = self.context.tables.get(table).unwrap();
+            let table_catalog = self
+                .context
+                .tables
+                .get(table)
+                .ok_or_else(|| BindError::InvalidTable(table.clone()))?;
             let column_catalog = table_catalog
                 .get_column_by_name(column_name)
                 .ok_or_else(|| BindError::InvalidColumn(column_name.clone()))?;
diff --git a/src/binder/table/mod.rs b/src/binder/table/mod.rs
index 266b7a4..da626fe 100644
--- a/src/binder/table/mod.rs
+++ b/src/binder/table/mod.rs
@@ -88,7 +88,7 @@ impl Binder {
 
     pub fn bind_table_ref(&mut self, table: &TableFactor) -> Result<BoundTableRef, BindError> {
         match table {
-            TableFactor::Table { name, alias: _, .. } => {
+            TableFactor::Table { name, alias, .. } => {
                 // ObjectName internal items: db.schema.table
                 let (_database, _schema, table) = match name.0.as_slice() {
                     [table] => (
@@ -114,18 +114,27 @@ impl Binder {
                     .catalog
                     .get_table_by_name(table)
                     .ok_or_else(|| BindError::InvalidTable(table_name.clone()))?;
-                self.context
-                    .tables
-                    .insert(table_name, table_catalog.clone());
-
+                if let Some(alias) = alias {
+                    let table_alias = alias.to_string().to_lowercase();
+                    self.context
+                        .tables
+                        .insert(table_alias, table_catalog.clone());
+                } else {
+                    self.context
+                        .tables
+                        .insert(table_name, table_catalog.clone());
+                }
                 Ok(BoundTableRef::Table(table_catalog))
             }
             TableFactor::Derived {
                 lateral: _,
                 subquery,
-                alias: _,
+                alias,
             } => {
                 let table = self.bind_select(subquery)?;
+                if let Some(alias) = alias {
+                    todo!("alias for subquery {}", alias)
+                }
                 Ok(BoundTableRef::Subquery(Box::new(table)))
             }
             _other => panic!("unsupported table factor: {:?}", _other),
diff --git a/tests/slt/alias.slt b/tests/slt/alias.slt
index 4d0f46a..620044b 100644
--- a/tests/slt/alias.slt
+++ b/tests/slt/alias.slt
@@ -1,3 +1,4 @@
+# expression alias
 query I
 select a as c1 from t1 order by c1 desc limit 1;
 ----
@@ -14,3 +15,28 @@ select sum(b) as c1, a as c2 from t1 group by c2 order by c1 desc;
 15 2
 5 1
 4 0
+
+# table alias
+query I
+select t.a from t1 t where t.b > 1 order by t.a desc limit 1;
+----
+2
+
+query I
+select sum(t.a) as c1 from t1 as t
+----
+5
+
+query I
+select t.* from t1 t where t.b > 1 order by t.a desc limit 1;
+----
+2 7 9
+
+query I
+select t_1.a from t1 t_1 left join t2 t_2 on t_1.a=t_2.b and t_1.c > t_2.c;
+----
+2
+2
+0
+1
+2