Add support for SHOW WARNINGS and SELECTs without a FROM (#2227)

Like SELECT 1, 'a';

Author: Jille

internal/compiler/output_columns.go

@@ -102,6 +102,24 @@ func outputColumns(qc *QueryCatalog, node ast.Node) ([]*Column, error) {
 		}
 		switch n := res.Val.(type) {
 
+		case *ast.A_Const:
+			name := ""
+			if res.Name != nil {
+				name = *res.Name
+			}
+			switch n.Val.(type) {
+			case *ast.String:
+				cols = append(cols, &Column{Name: name, DataType: "text", NotNull: true})
+			case *ast.Integer:
+				cols = append(cols, &Column{Name: name, DataType: "int", NotNull: true})
+			case *ast.Float:
+				cols = append(cols, &Column{Name: name, DataType: "float", NotNull: true})
+			case *ast.Boolean:
+				cols = append(cols, &Column{Name: name, DataType: "bool", NotNull: true})
+			default:
+				cols = append(cols, &Column{Name: name, DataType: "any", NotNull: false})
+			}
+
 		case *ast.A_Expr:
 			name := ""
 			if res.Name != nil {

internal/endtoend/testdata/diff_no_output/go/query.sql.go

@@ -46,9 +46,9 @@
 +SELECT 1
 +`
 +
-+func (q *Queries) SelectOne(ctx context.Context) (interface{}, error) {
++func (q *Queries) SelectOne(ctx context.Context) (int32, error) {
 +	row := q.db.QueryRowContext(ctx, selectOne)
-+	var column_1 interface{}
++	var column_1 int32
 +	err := row.Scan(&column_1)
 +	return column_1, err
 +}

internal/endtoend/testdata/diff_output/stderr.txt

@@ -0,0 +1,2 @@
+-- name: SelectStatic :one
+SELECT 'a', 'b' AS b, 1 AS num, true AS truefield, 1.0 AS floater

internal/endtoend/testdata/selectstatic/mysql/go/db.go

@@ -0,0 +1,13 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "sql_package": "database/sql",
+      "engine": "mysql",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}

internal/endtoend/testdata/selectstatic/mysql/go/models.go

@@ -0,0 +1,2 @@
+-- name: ShowWarnings :many
+SHOW WARNINGS;

internal/endtoend/testdata/selectstatic/mysql/go/query.sql.go

@@ -0,0 +1,12 @@
+{
+  "version": "1",
+  "packages": [
+    {
+      "path": "go",
+      "engine": "mysql",
+      "name": "querytest",
+      "schema": "query.sql",
+      "queries": "query.sql"
+    }
+  ]
+}

internal/endtoend/testdata/selectstatic/mysql/query.sql

@@ -6,6 +6,7 @@ import (
 	"strings"
 
 	pcast "github.com/pingcap/tidb/parser/ast"
+	"github.com/pingcap/tidb/parser/mysql"
 	"github.com/pingcap/tidb/parser/opcode"
 	driver "github.com/pingcap/tidb/parser/test_driver"
 	"github.com/pingcap/tidb/parser/types"
@@ -580,6 +581,41 @@ func (c *cc) convertUpdateStmt(n *pcast.UpdateStmt) *ast.UpdateStmt {
 }
 
 func (c *cc) convertValueExpr(n *driver.ValueExpr) *ast.A_Const {
+	switch n.TexprNode.Type.GetType() {
+	case mysql.TypeBit:
+	case mysql.TypeDate:
+	case mysql.TypeDatetime:
+	case mysql.TypeGeometry:
+	case mysql.TypeJSON:
+	case mysql.TypeNull:
+	case mysql.TypeSet:
+	case mysql.TypeShort:
+	case mysql.TypeDuration:
+	case mysql.TypeTimestamp:
+		// TODO: Create an AST type for these?
+
+	case mysql.TypeTiny,
+		mysql.TypeInt24,
+		mysql.TypeYear,
+		mysql.TypeLong,
+		mysql.TypeLonglong:
+		return &ast.A_Const{
+			Val: &ast.Integer{
+				Ival: n.Datum.GetInt64(),
+			},
+		}
+
+	case mysql.TypeDouble,
+		mysql.TypeFloat,
+		mysql.TypeNewDecimal:
+		return &ast.A_Const{
+			Val: &ast.Float{
+				// TODO: Extract the value from n.TexprNode
+			},
+		}
+
+	case mysql.TypeBlob, mysql.TypeString, mysql.TypeVarchar, mysql.TypeVarString, mysql.TypeLongBlob, mysql.TypeMediumBlob, mysql.TypeTinyBlob, mysql.TypeEnum:
+	}
 	return &ast.A_Const{
 		Val: &ast.String{
 			Str: n.Datum.GetString(),
@@ -1219,7 +1255,32 @@ func (c *cc) convertSetStmt(n *pcast.SetStmt) ast.Node {
 }
 
 func (c *cc) convertShowStmt(n *pcast.ShowStmt) ast.Node {
-	return todo(n)
+	if n.Tp != pcast.ShowWarnings {
+		return todo(n)
+	}
+	level := "level"
+	code := "code"
+	message := "message"
+	stmt := &ast.SelectStmt{
+		FromClause: &ast.List{},
+		TargetList: &ast.List{
+			Items: []ast.Node{
+				&ast.ResTarget{
+					Name: &level,
+					Val:  &ast.A_Const{Val: &ast.String{}},
+				},
+				&ast.ResTarget{
+					Name: &code,
+					Val:  &ast.A_Const{Val: &ast.Integer{}},
+				},
+				&ast.ResTarget{
+					Name: &message,
+					Val:  &ast.A_Const{Val: &ast.String{}},
+				},
+			},
+		},
+	}
+	return stmt
 }
 
 func (c *cc) convertShutdownStmt(n *pcast.ShutdownStmt) ast.Node {