[proposal] Support _add

[int8259]

There're many cases that user want to use aop to filter data, like soft delete. By adding support for '_add', it enables users to implement AOP queries more easily.

just like：

bllWhere := map[string]interface{}{
	"country":      "China",
	"role":         "driver",
	"age >":        45,
	"gmt_create <": builder.Raw("gmt_modified"),
	"_or": []map[string]interface{}{
		{
			"x1":    11,
			"x2 >=": 45,
		},
		{
			"x3":    "234",
			"x4 <>": "tx2",
		},
	},
}

aopWhere := map[string]interface{}{
	"_and": []map[string]interface{}{
	{
	      "is_del": 0,
        },        
	     bllWhere,
        },
}

[caibirdme]

Sorry I don't understand what AOP exact mean in your case

[int8259]

When writing business logic, it’s always done with bllWhere. When invoking, AOP should automatically inject conditions similar to {"is_del": 1} based on the context. Just like:
aopWhere
aop1
aop2
aop3

bllWhere
bll1
bll2
bll3

During execution, an algorithm needs to select an appropriate aopWhere, which is then combined with a specific bll to ultimately perform the query.

[caibirdme]

Why not just BuildSelect(YourAOP(where))

[int8259]

In IoT scenarios, when the MES system queries data, there are sometimes interactions with external systems to confirm AOP query requests. There can be situations like the following:
Items are divided by weight specifications.

aopWhere = {
"weight >": 10
}

bllWhere = {
"weight >": 20
}

Using YourAOP(bllWhere) means that developers need to parse SQL requests and perform boolean operations. By adding _add, the sql engine can parse (aopCond AND (bllCond)).