diff --git a/expression/in.go b/expression/in.go
index 1523aa348b324..3edc30a131bdf 100644
--- a/expression/in.go
+++ b/expression/in.go
@@ -142,14 +142,15 @@ func (n *PatternIn) Eval(ctx context.Context, args map[interface{}]interface{})
 	}
 
 	if n.Sel == nil {
-		if err := hasSameColumnCount(ctx, n.Expr, n.List...); err != nil {
-			return nil, errors.Trace(err)
+		err1 := hasSameColumnCount(ctx, n.Expr, n.List...)
+		if err1 != nil {
+			return nil, errors.Trace(err1)
 		}
 
 		var values []interface{}
-		values, err = evalExprList(ctx, args, n.List)
-		if err != nil {
-			return nil, errors.Trace(err)
+		values, err1 = evalExprList(ctx, args, n.List)
+		if err1 != nil {
+			return nil, errors.Trace(err1)
 		}
 
 		return n.checkInList(lhs, values)
diff --git a/expression/isnull.go b/expression/isnull.go
index 428777761a676..13bba740e00d7 100644
--- a/expression/isnull.go
+++ b/expression/isnull.go
@@ -54,14 +54,14 @@ func (is *IsNull) String() string {
 }
 
 // Eval implements the Expression Eval interface.
-func (is *IsNull) Eval(ctx context.Context, args map[interface{}]interface{}) (v interface{}, err error) {
+func (is *IsNull) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
 	if err := CheckOneColumn(ctx, is.Expr); err != nil {
 		return nil, errors.Trace(err)
 	}
 
 	val, err := is.Expr.Eval(ctx, args)
 	if err != nil {
-		return
+		return nil, errors.Trace(err)
 	}
 
 	return types.IsNil(val) != is.Not, nil
diff --git a/expression/istruth.go b/expression/istruth.go
index 5df1f43fa389c..61b2bfebd5a50 100644
--- a/expression/istruth.go
+++ b/expression/istruth.go
@@ -63,14 +63,14 @@ func (is *IsTruth) String() string {
 }
 
 // Eval implements the Expression Eval interface.
-func (is *IsTruth) Eval(ctx context.Context, args map[interface{}]interface{}) (v interface{}, err error) {
+func (is *IsTruth) Eval(ctx context.Context, args map[interface{}]interface{}) (interface{}, error) {
 	if err := CheckOneColumn(ctx, is.Expr); err != nil {
 		return nil, errors.Trace(err)
 	}
 
 	val, err := is.Expr.Eval(ctx, args)
 	if err != nil {
-		return
+		return nil, errors.Trace(err)
 	}
 
 	if types.IsNil(val) {
@@ -81,7 +81,7 @@ func (is *IsTruth) Eval(ctx context.Context, args map[interface{}]interface{}) (
 
 	b, err := types.ToBool(val)
 	if err != nil {
-		return
+		return nil, errors.Trace(err)
 	}
 
 	if !is.Not {
diff --git a/interpreter/main.go b/interpreter/main.go
index 95d6f00c89020..e679defd39495 100644
--- a/interpreter/main.go
+++ b/interpreter/main.go
@@ -205,7 +205,7 @@ func main() {
 				}
 
 				if strings.HasPrefix(txnLine, "COMMIT") || strings.HasPrefix(txnLine, "commit") {
-					err := tx.Commit()
+					err = tx.Commit()
 					if err != nil {
 						log.Error(errors.ErrorStack(err))
 						tx.Rollback()
diff --git a/plan/plans/groupby.go b/plan/plans/groupby.go
index ffdba3e5f0890..8e224a6518e74 100644
--- a/plan/plans/groupby.go
+++ b/plan/plans/groupby.go
@@ -275,14 +275,14 @@ func (r *GroupByDefaultPlan) fetchAll(ctx context.Context) error {
 		// TODO: later order by will use the same mechanism, so we may use another plan to do this
 		evalArgs := map[interface{}]interface{}{}
 		// must first eval none aggregate fields, because alias group by will use this.
-		if err := r.evalNoneAggFields(ctx, row.Data, evalArgs, srcRow.Data); err != nil {
+		if err = r.evalNoneAggFields(ctx, row.Data, evalArgs, srcRow.Data); err != nil {
 			return errors.Trace(err)
 		}
 
 		// update outer query becuase group by may use it if it has a subquery.
 		updateRowStack(ctx, row.Data, row.FromData)
 
-		if err := r.evalGroupKey(ctx, k, row.Data, srcRow.Data); err != nil {
+		if err = r.evalGroupKey(ctx, k, row.Data, srcRow.Data); err != nil {
 			return errors.Trace(err)
 		}
 
@@ -298,7 +298,7 @@ func (r *GroupByDefaultPlan) fetchAll(ctx context.Context) error {
 			index = len(r.rows)
 			r.rows = append(r.rows, &groupRow{Row: row, Args: evalArgs})
 
-			if err := t.Set(k, []interface{}{index}); err != nil {
+			if err = t.Set(k, []interface{}{index}); err != nil {
 				return errors.Trace(err)
 			}
 		} else {
@@ -310,7 +310,7 @@ func (r *GroupByDefaultPlan) fetchAll(ctx context.Context) error {
 		}
 
 		// eval aggregate fields
-		if err := r.evalAggFields(ctx, row.Data, evalArgs, srcRow.Data); err != nil {
+		if err = r.evalAggFields(ctx, row.Data, evalArgs, srcRow.Data); err != nil {
 			return errors.Trace(err)
 		}
 	}
@@ -326,7 +326,7 @@ func (r *GroupByDefaultPlan) fetchAll(ctx context.Context) error {
 	} else {
 		for _, row := range r.rows {
 			// eval aggregate done
-			if err := r.evalAggDone(ctx, row.Row.Data, row.Args); err != nil {
+			if err = r.evalAggDone(ctx, row.Row.Data, row.Args); err != nil {
 				return errors.Trace(err)
 			}
 		}
diff --git a/rset/rsets/join.go b/rset/rsets/join.go
index 8d343cd51b7cd..bc63556ef07a9 100644
--- a/rset/rsets/join.go
+++ b/rset/rsets/join.go
@@ -214,7 +214,7 @@ func (r *JoinRset) buildSourcePlan(ctx context.Context, t *TableSource) (plan.Pl
 			return nil, nil, errors.Trace(err)
 		}
 		src = tr
-		if err := r.checkTableDuplicate(t, tr); err != nil {
+		if err = r.checkTableDuplicate(t, tr); err != nil {
 			return nil, nil, errors.Trace(err)
 		}
 	case stmt.Statement:
diff --git a/table/tables/tables.go b/table/tables/tables.go
index 8e917545ede3e..f3acf3d1ccd4f 100644
--- a/table/tables/tables.go
+++ b/table/tables/tables.go
@@ -470,7 +470,7 @@ func (t *Table) removeRowData(ctx context.Context, h int64) error {
 	// Remove row's colume one by one
 	for _, col := range t.Cols() {
 		k := t.RecordKey(h, col)
-		err := txn.Delete([]byte(k))
+		err = txn.Delete([]byte(k))
 		if err != nil {
 			return errors.Trace(err)
 		}