fix: The HasConstraint is fixed by adding a Unique Check

migrator.go

@@ -396,31 +396,55 @@ WHERE TABLE_CATALOG = ? AND TABLE_NAME = ?`)
 
 		{
 			_, schemaName, tableName := splitFullQualifiedName(stmt.Table)
-			query := "SELECT c.COLUMN_NAME, t.CONSTRAINT_TYPE FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS t JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE c ON c.CONSTRAINT_NAME=t.CONSTRAINT_NAME WHERE t.CONSTRAINT_TYPE IN ('PRIMARY KEY', 'UNIQUE') AND c.TABLE_CATALOG = ? AND c.TABLE_NAME = ?"
+
+			query := "SELECT t.CONSTRAINT_NAME FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS t JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE c ON c.CONSTRAINT_NAME=t.CONSTRAINT_NAME WHERE t.CONSTRAINT_TYPE IN ('PRIMARY KEY', 'UNIQUE') AND c.TABLE_CATALOG = ? AND c.TABLE_NAME = ? AND CONSTRAINT_TYPE = ?"
 
 			queryParameters := []interface{}{m.CurrentDatabase(), tableName}
 
 			if schemaName != "" {
 				query += " AND c.TABLE_SCHEMA = ?"
 				queryParameters = append(queryParameters, schemaName)
 			}
-
+			queryParameters = append(queryParameters, "UNIQUE")
 			columnTypeRows, err := m.DB.Raw(query, queryParameters...).Rows()
 			if err != nil {
 				return err
 			}
+			uniqueContraints := map[string]int{}
+			for columnTypeRows.Next() {
+				var constraintName string
+				columnTypeRows.Scan(&constraintName)
+				uniqueContraints[constraintName]++
+			}
+			_ = columnTypeRows.Close()
+
+			query = "SELECT c.COLUMN_NAME, t.CONSTRAINT_NAME, t.CONSTRAINT_TYPE FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS t JOIN INFORMATION_SCHEMA.CONSTRAINT_COLUMN_USAGE c ON c.CONSTRAINT_NAME=t.CONSTRAINT_NAME WHERE t.CONSTRAINT_TYPE IN ('PRIMARY KEY', 'UNIQUE') AND c.TABLE_CATALOG = ? AND c.TABLE_NAME = ?"
+
+			queryParameters = []interface{}{m.CurrentDatabase(), tableName}
+
+			if schemaName != "" {
+				query += " AND c.TABLE_SCHEMA = ?"
+				queryParameters = append(queryParameters, schemaName)
+			}
+
+			columnTypeRows, err = m.DB.Raw(query, queryParameters...).Rows()
+			if err != nil {
+				return err
+			}
 
 			for columnTypeRows.Next() {
-				var name, columnType string
-				_ = columnTypeRows.Scan(&name, &columnType)
+				var name, constraintName, columnType string
+				_ = columnTypeRows.Scan(&name, &constraintName, &columnType)
 				for idx, c := range columnTypes {
 					mc := c.(migrator.ColumnType)
 					if mc.NameValue.String == name {
 						switch columnType {
 						case "PRIMARY KEY":
 							mc.PrimaryKeyValue = sql.NullBool{Bool: true, Valid: true}
 						case "UNIQUE":
-							mc.UniqueValue = sql.NullBool{Bool: true, Valid: true}
+							if uniqueContraints[constraintName] == 1 {
+								mc.UniqueValue = sql.NullBool{Bool: true, Valid: true}
+							}
 						}
 						columnTypes[idx] = mc
 						break
@@ -573,17 +597,29 @@ func (m Migrator) HasConstraint(value interface{}, name string) bool {
 
 		return m.DB.Raw(
 			`SELECT count(*) FROM (
+				-- Check CHECK constraint
 				SELECT C.name, T.name as table_name FROM sys.check_constraints as C 
 				INNER JOIN sys.tables as T on C.parent_object_id=T.object_id 
 				INNER JOIN INFORMATION_SCHEMA.TABLES as I on I.TABLE_NAME = T.name 
 				WHERE C.name = ? AND I.TABLE_NAME = ? AND I.TABLE_SCHEMA like ? AND I.TABLE_CATALOG = ?
 				UNION
+				-- Check foreign key constraints
 				SELECT FK.name, T.name as table_name FROM sys.foreign_keys as FK 
 				INNER JOIN sys.tables as T on FK.parent_object_id=T.object_id 
 				INNER JOIN INFORMATION_SCHEMA.TABLES as I on I.TABLE_NAME = T.name 
 				WHERE FK.name = ? AND I.TABLE_NAME = ? AND I.TABLE_SCHEMA like ? AND I.TABLE_CATALOG = ?
+				UNION
+				-- Check Unique Constraint
+				SELECT UK.name, T.name as table_name FROM sys.key_constraints as UK 
+				INNER JOIN sys.tables as T on UK.parent_object_id = T.object_id 
+				INNER JOIN INFORMATION_SCHEMA.TABLES as I on I.TABLE_NAME = T.name 
+				WHERE UK.type = 'UQ' AND UK.name = ? AND I.TABLE_NAME = ? AND I.TABLE_SCHEMA like ? AND I.TABLE_CATALOG = ?
 			) as constraints;`,
+			// CHECK constraint parameter
+			name, tableName, tableSchema, tableCatalog,
+			// Foreign key constraint parameters
 			name, tableName, tableSchema, tableCatalog,
+			// Unique Constraint Parameter
 			name, tableName, tableSchema, tableCatalog,
 		).Row().Scan(&count)
 	})

migrator_test.go

@@ -208,6 +208,36 @@ type TestTableFieldCommentUpdate struct {
 
 func (*TestTableFieldCommentUpdate) TableName() string { return "test_table_field_comment" }
 
+type TestTableFieldUnique struct {
+	ID   string `gorm:"column:id;primaryKey;comment:"` // field comment is an empty string
+	Name string `gorm:"column:name;unique;comment:姓名"`
+	Age  uint   `gorm:"column:age;comment:年龄"`
+}
+
+func (*TestTableFieldUnique) TableName() string { return "test_table_field_unique" }
+
+func TestHasConstraint(t *testing.T) {
+	db, err := gorm.Open(sqlserver.Open(sqlserverDSN))
+	if err != nil {
+		t.Fatal(err)
+	}
+	dm := db.Debug().Migrator()
+	tableModel := new(TestTableFieldUnique)
+	defer func() {
+		if err = dm.DropTable(tableModel); err != nil {
+			t.Errorf("couldn't drop table %q, got error: %v", tableModel.TableName(), err)
+		}
+	}()
+
+	if err = dm.AutoMigrate(tableModel); err != nil {
+		t.Fatal(err)
+	}
+	hasName := dm.HasConstraint(tableModel, "name")
+	if !hasName {
+		t.Fatalf("expected unique")
+	}
+}
+
 func TestMigrator_MigrateColumnComment(t *testing.T) {
 	db, err := gorm.Open(sqlserver.Open(sqlserverDSN))
 	if err != nil {