1. 实现配置文件解析

2. 实现数据库连接

vendor/gorm.io/gorm/clause/limit.go

@@ -0,0 +1,46 @@
+package clause
+
+// Limit limit clause
+type Limit struct {
+	Limit  *int
+	Offset int
+}
+
+// Name where clause name
+func (limit Limit) Name() string {
+	return "LIMIT"
+}
+
+// Build build where clause
+func (limit Limit) Build(builder Builder) {
+	if limit.Limit != nil && *limit.Limit >= 0 {
+		builder.WriteString("LIMIT ")
+		builder.AddVar(builder, *limit.Limit)
+	}
+	if limit.Offset > 0 {
+		if limit.Limit != nil && *limit.Limit >= 0 {
+			builder.WriteByte(' ')
+		}
+		builder.WriteString("OFFSET ")
+		builder.AddVar(builder, limit.Offset)
+	}
+}
+
+// MergeClause merge order by clauses
+func (limit Limit) MergeClause(clause *Clause) {
+	clause.Name = ""
+
+	if v, ok := clause.Expression.(Limit); ok {
+		if (limit.Limit == nil || *limit.Limit == 0) && v.Limit != nil {
+			limit.Limit = v.Limit
+		}
+
+		if limit.Offset == 0 && v.Offset > 0 {
+			limit.Offset = v.Offset
+		} else if limit.Offset < 0 {
+			limit.Offset = 0
+		}
+	}
+
+	clause.Expression = limit
+}