1. 实现配置文件解析

2. 实现数据库连接

vendor/gorm.io/gorm/clause/update.go

@@ -0,0 +1,38 @@
+package clause
+
+type Update struct {
+	Modifier string
+	Table    Table
+}
+
+// Name update clause name
+func (update Update) Name() string {
+	return "UPDATE"
+}
+
+// Build build update clause
+func (update Update) Build(builder Builder) {
+	if update.Modifier != "" {
+		builder.WriteString(update.Modifier)
+		builder.WriteByte(' ')
+	}
+
+	if update.Table.Name == "" {
+		builder.WriteQuoted(currentTable)
+	} else {
+		builder.WriteQuoted(update.Table)
+	}
+}
+
+// MergeClause merge update clause
+func (update Update) MergeClause(clause *Clause) {
+	if v, ok := clause.Expression.(Update); ok {
+		if update.Modifier == "" {
+			update.Modifier = v.Modifier
+		}
+		if update.Table.Name == "" {
+			update.Table = v.Table
+		}
+	}
+	clause.Expression = update
+}