NewReadMe.md

New Update and UpdateAsync upgrade: CASE

A new feature added to allow developers to programmatically set CASE WHEN when assigning values. Feature includes grouping in sub statements () or

to allow condition to point to a column variable instead of a direct paramater value. SQL injection friendly

Original Update Statement for multiple records using anonymous objects:

foreach (var item in data)

{

object obj = new

{

MyField = item.Value

};

cnt += await QueryFactory.Query(tableName).Where("Id", item.Id).UpdateAsync(value);

}

return cnt;

New Update with select case using multi-level array systems

version 1 : allows is equal condition only for now

For the Else it will always fill with name of field itself , self assigning.

This happens if format is wrong as well.

The else protects you fro your field to be set back to NULL

Warning: Limitation is requires , Suggest 200 rows for low number columns,

25 for higher number columns or clauses.

 var datac = data.Chunk(200); // breaking data up to 200 rows

 //each holds for each  update set, which allows multiple value setting as older Update
 List<object[]> cases = [];  

 if (datac.Any()) foreach (var d in datac)
 {
   
     try
     {                   
         foreach (var item in d)   //Build case when statement , standard 3
         {
             cases.Add(["Id", item.Id, item.Value]); 
         }
         object obj = new
         {
             MyField= cases.ToArray()
         };
         cases.Clear();

         //if data set is smaller than whole table , best to use in statement to reduce cost
         cnt += await QueryFactory.Query(tableName)
                .WhereIn("Id", d.Select(dd => dd.Id).ToArray())
                .UpdateAsync(value);             
     }
     catch { throw; }
     finally { cases.Clear();  }
 }
 else cases.Clear();

 return cnt;    

##standard: Case WHEN x = A then Y... END:

In your cases array the flow is [x,A,Y].

Assignmet value is always last.

Available Feaure 1 : While its common to do 3 items for basic, when can extend the criteria with AND and OR

It combine, the array column after the orevioud criteria field must be an AND or OR, unless using , () or * explained later

Note: Assignmet value is always last. you can use AND,&&,& or OR,||,|, <>. Not case sensitive.

Case WHEN x = A AND z = B then Y ... END:

In your cases array the flow is [x,A,"AND",z,B,Y]

Case WHEN x = A OR z = B then Y ... END:

Array the flow is [x,A,"OR",z,B,Y]

Available Feaure 2 : Subset (). This allows seperating your "And" & "Or" blocks

ex: case when (a = 1 or a = 5) and (b = 7 and c = 2)

This can be placed anywhere before the assignment column or * assignment column,

if you forget to add the ) to close, the engine

will compensate.

Case WHEN (x = A AND z = B) OR J = C then Y ... END:

Array the flow is ["(",x,A,"AND",z,B,")","OR",j,c,Y]

Case WHEN (x = A OR z = B) AND (J = C AND K = D) then Y ... END:

Array the flow is ["(",x,A,"OR",z,B,")","AND","(",j,c,"AND",k,d,")" Y]

Available Feaure 3 : To Another Column Field (*). This allows criteria to check if column equals another column (field)

Case WHEN (colx = colb AND colz = colx) then Y ... END:

Array the flow is [,colx,*',colb,"AND",colz,colx, Y]