add create table nil default

Author: elianddb

sql/planbuilder/ddl.go

@@ -1419,6 +1419,15 @@ func (b *Builder) tableSpecToSchema(inScope, outScope *scope, db sql.Database, t
 
 	for i, def := range defaults {
 		schema[i].Default = b.convertDefaultExpression(outScope, def, schema[i].Type, schema[i].Nullable)
+		if schema[i].Default == nil && schema[i].Nullable {
+			schema[i].Default = &sql.ColumnDefaultValue{
+				Expr:          expression.NewLiteral(nil, schema[i].Type),
+				OutType:       nil,
+				Literal:       true,
+				Parenthesized: false,
+				ReturnNil:     true,
+			}
+		}
 		err := validateDefaultExprs(schema[i])
 		if err != nil {
 			b.handleErr(err)

sql/planbuilder/dml.go

@@ -75,12 +75,24 @@ func (b *Builder) buildInsert(inScope *scope, i *ast.Insert) (outScope *scope) {
 		if len(columns) == 0 && len(destScope.cols) > 0 && rt != nil {
 			schema := rt.Schema()
 			columns = make([]string, len(schema))
-			for i, col := range schema {
+			for index, col := range schema {
 				// Tables with any generated column must always supply a column list, so this is always an error
 				if col.Generated != nil {
 					b.handleErr(sql.ErrGeneratedColumnValue.New(col.Name, rt.Name()))
 				}
-				columns[i] = col.Name
+				columns[index] = col.Name
+			}
+			if ir, ok := i.Rows.(*ast.AliasedValues); ok && len(ir.Values[0]) == 0 {
+				// VALUES() clause is empty in conjunction with empty column list, so we need to
+				// insert default val for respective columns.
+				ir.Values[0] = make([]ast.Expr, len(schema))
+				for j, col := range schema {
+					if col.Default == nil {
+						b.handleErr(sql.ErrInsertIntoNonNullableDefaultNullColumn.New(col.Name))
+					}
+
+					ir.Values[0][j] = &ast.Default{}
+				}
 			}
 		}
 	}
@@ -214,8 +226,6 @@ func (b *Builder) buildInsertValues(inScope *scope, v *ast.AliasedValues, column
 	literalOnly = true
 	exprTuples := make([][]sql.Expression, len(v.Values))
 	for i, vt := range v.Values {
-		// noExprs is an edge case where we fill VALUES with nil expressions
-		//noExprs := len(vt) == 0
 		// triggerUnknownTable is an edge case where we ignored an unresolved
 		// table error and do not have a schema for resolving defaults
 		triggerUnknownTable := (len(columnNames) == 0 && len(vt) > 0) && (len(b.TriggerCtx().UnresolvedTables) > 0)