Update handling of SHOW COLUMNs/SHOW DATABASE

Author: alamb

datafusion/sql/src/statement.rs

@@ -54,13 +54,13 @@ use datafusion_expr::{
     TransactionConclusion, TransactionEnd, TransactionIsolationLevel, TransactionStart,
     Volatility, WriteOp,
 };
-use sqlparser::ast::{self, ShowStatementOptions, SqliteOnConflict};
+use sqlparser::ast::{self, ShowStatementIn, ShowStatementOptions, SqliteOnConflict};
 use sqlparser::ast::{
     Assignment, AssignmentTarget, ColumnDef, CreateIndex, CreateTable,
     CreateTableOptions, Delete, DescribeAlias, Expr as SQLExpr, FromTable, Ident, Insert,
     ObjectName, ObjectType, OneOrManyWithParens, Query, SchemaName, SetExpr,
-    ShowCreateObject, ShowStatementFilter, Statement, TableConstraint, TableFactor,
-    TableWithJoins, TransactionMode, UnaryOperator, Value,
+    ShowCreateObject, Statement, TableConstraint, TableFactor, TableWithJoins,
+    TransactionMode, UnaryOperator, Value,
 };
 use sqlparser::parser::ParserError::ParserError;
 
@@ -735,12 +735,49 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
             Statement::ShowColumns {
                 extended,
                 full,
-                //table_name,
-                //filter,
-                show_options: _,
+                show_options,
             } => {
-                todo!("Update show columns / fix for new syntax");
-                //self.show_columns_to_plan(extended, full, table_name, filter)
+                let ShowStatementOptions {
+                    show_in,
+                    starts_with,
+                    limit,
+                    limit_from,
+                    filter_position,
+                } = show_options;
+                if starts_with.is_some() {
+                    return not_impl_err!("SHOW COLUMNS LIKE not supported")?;
+                }
+                if limit.is_some() {
+                    return not_impl_err!("SHOW COLUMNS LIMIT not supported")?;
+                }
+                if limit_from.is_some() {
+                    return not_impl_err!("SHOW COLUMNS LIMIT FROM not supported")?;
+                }
+                if filter_position.is_some() {
+                    return not_impl_err!("SHOW COLUMNS FILTER not supported")?;
+                }
+                if filter_position.is_some() {
+                    return not_impl_err!("SHOW COLUMNS FILTER not supported")?;
+                }
+                let Some(ShowStatementIn {
+                    // specifies if the syntax was `SHOW COLUMNS IN` or `SHOW
+                    // COLUMNS FROM` which is not different in DataFusion
+                    clause: _,
+                    parent_type,
+                    parent_name,
+                }) = show_in
+                else {
+                    return plan_err!("SHOW COLUMNS requires a table name");
+                };
+
+                if let Some(parent_type) = parent_type {
+                    return not_impl_err!("SHOW COLUMNS IN {parent_type} not supported");
+                }
+                let Some(table_name) = parent_name else {
+                    return plan_err!("SHOW COLUMNS requires a table name");
+                };
+
+                self.show_columns_to_plan(extended, full, table_name)
             }
 
             Statement::Insert(Insert {
@@ -1878,17 +1915,7 @@ impl<'a, S: ContextProvider> SqlToRel<'a, S> {
         extended: bool,
         full: bool,
         sql_table_name: ObjectName,
-        filter: Option<ShowStatementFilter>,
     ) -> Result<LogicalPlan> {
-        if filter.is_some() {
-            return plan_err!("SHOW COLUMNS with WHERE or LIKE is not supported");
-        }
-
-        if !self.has_table("information_schema", "columns") {
-            return plan_err!(
-                "SHOW COLUMNS is not supported unless information_schema is enabled"
-            );
-        }
         // Figure out the where clause
         let where_clause = object_name_to_qualifier(
             &sql_table_name,