LINQ implements query string concatenation: And and or two ways

N years ago we did this to splice the query string:

      Public stringTest (stringAstringBstringCstringd) {stringsql ="SELECT * from Users WHERE 1=1"; if(!string. IsNullOrEmpty (a)) {SQL+="and name= '"+ A +"'"; }            if(!string. IsNullOrEmpty (b)) {SQL+="and age= '"+ B +"'"; }            if(!string. IsNullOrEmpty (c)) {SQL+="and sex= '"+ C +"'"; }            if(!string. IsNullOrEmpty (d)) {SQL+="and address= '"+ D +"'"; }            returnSQL.        ToString (); }

Now we use LINQ to implement the above code:

  Public voidTest (stringAstringBstringCstringd) {querycontext query=NewQuerycontext (); varQ = fromUinchquery. UsersSelectu; if(!string. IsNullOrEmpty (a)) {Q= Q.where (p = = P.name = =a); }            if(!string. IsNullOrEmpty (b)) {Q= Q.where (p = = P.age = =b); }            if(!string. IsNullOrEmpty (c)) {Q= Q.where (p = = P.sex = =c); }            if(!string. IsNullOrEmpty (d)) {Q= Q.where (p = = P.address = =d);  } q.tolist (); //all of the above if, only to be executed here}

PS: If the query string is not and, but is or

Such as:

      Public stringTest (stringAstringBstringCstringd) {stringsql ="SELECT * from Users WHERE 1=1"; if(!string. IsNullOrEmpty (a)) {SQL+="OR name= '"+ A +"'"; }            if(!string. IsNullOrEmpty (b)) {SQL+="OR age= '"+ B +"'"; }            if(!string. IsNullOrEmpty (c)) {SQL+="OR sex= '"+ C +"'"; }            if(!string. IsNullOrEmpty (d)) {SQL+="OR address= '"+ D +"'"; }            returnSQL.        ToString (); }

In this case, this can be achieved through LINQ:

     Public voidTest (stringAstringBstringCstringd) {querycontext query=NewQuerycontext (); varQ1 = fromUinchquery. Userswhereu.name== a && a! =""|| U.age = = B && b! =""|| U.sex = = c && c! =""|| U.address ==d && D! =""                           Selectu; Q1.        ToList (); }

LINQ implements query string concatenation: And and or two ways