1. 实现配置文件解析

2. 实现数据库连接

vendor/gorm.io/gorm/clause/on_conflict.go

@@ -0,0 +1,59 @@
+package clause
+
+type OnConflict struct {
+	Columns      []Column
+	Where        Where
+	TargetWhere  Where
+	OnConstraint string
+	DoNothing    bool
+	DoUpdates    Set
+	UpdateAll    bool
+}
+
+func (OnConflict) Name() string {
+	return "ON CONFLICT"
+}
+
+// Build build onConflict clause
+func (onConflict OnConflict) Build(builder Builder) {
+	if onConflict.OnConstraint != "" {
+		builder.WriteString("ON CONSTRAINT ")
+		builder.WriteString(onConflict.OnConstraint)
+		builder.WriteByte(' ')
+	} else {
+		if len(onConflict.Columns) > 0 {
+			builder.WriteByte('(')
+			for idx, column := range onConflict.Columns {
+				if idx > 0 {
+					builder.WriteByte(',')
+				}
+				builder.WriteQuoted(column)
+			}
+			builder.WriteString(`) `)
+		}
+
+		if len(onConflict.TargetWhere.Exprs) > 0 {
+			builder.WriteString(" WHERE ")
+			onConflict.TargetWhere.Build(builder)
+			builder.WriteByte(' ')
+		}
+	}
+
+	if onConflict.DoNothing {
+		builder.WriteString("DO NOTHING")
+	} else {
+		builder.WriteString("DO UPDATE SET ")
+		onConflict.DoUpdates.Build(builder)
+	}
+
+	if len(onConflict.Where.Exprs) > 0 {
+		builder.WriteString(" WHERE ")
+		onConflict.Where.Build(builder)
+		builder.WriteByte(' ')
+	}
+}
+
+// MergeClause merge onConflict clauses
+func (onConflict OnConflict) MergeClause(clause *Clause) {
+	clause.Expression = onConflict
+}