Database Component hxj. Data (27th) (Field combination update)

Hxj. Data v1.5.1 supports field combination update.

Example: Update table set A = B + C

Update table set a = a + 1

(+,-, *,/, %) And so on.

 

The following is an example. (The example only serves to test the effect and has no practical significance)

Example 1,

DbSession.Default.Update<Products>(Products._.UnitPrice, Products._.ReorderLevel + Products._.UnitPrice, Products._.ProductID == 1);

The generated SQL statement is as follows:

Text: 

UPDATE [Products] SET [UnitPrice]=[Products].[ReorderLevel] + [Products].[UnitPrice] 

WHERE [Products].[ProductID] = @mjpxqimmtmiyguvv 

Parameters: 

@mjpxqimmtmiyguvv[Int32] = 1 

Update the value of the unitprice field to the value of the reorderlevel field added to unitprice.

 

Example 2,

DbSession.Default.Update<Products>(Products._.UnitPrice, Products._.UnitPrice + 1, Products._.ProductID == 1);

The generated SQL statement is as follows:

Text: 

UPDATE [Products] SET [UnitPrice]=[Products].[UnitPrice] + @tszvynxwnukkjuzj 

WHERE [Products].[ProductID] = @anuixieadujzvvka 

Parameters: 

@tszvynxwnukkjuzj[Int32] = 1 

@anuixieadujzvvka[Int32] = 1 

Add the value of the unitprice field to 1.

Example 3,

using (DbTrans trans = DbSession.Default.BeginTransaction()){    trans.Update<Products>(Products._.UnitPrice, Products._.UnitPrice + 1.4, Products._.ProductID == 1);    trans.Update<Products>(Products._.UnitPrice, Products._.UnitPrice - 2, Products._.ProductID == 2);    trans.Commit();}

Generated SQL:

Text: 

UPDATE [Products] SET [UnitPrice]=[Products].[UnitPrice] + @zeylmhakevldbgfn 

WHERE [Products].[ProductID] = @enbemtqnigeugdej 

Parameters: 

@zeylmhakevldbgfn[Double] = 1.4 

@enbemtqnigeugdej[Int32] = 1 

Text: 

UPDATE [Products] SET [UnitPrice]=[Products].[UnitPrice] - @vypfmbnjgdpeakqm 

WHERE [Products].[ProductID] = @dqwlfxqjconzrqa 

Parameters: 

@vypfmbnjgdpeakqm[Int32] = 2 

@dqwlfxqjconzrqa[Int32] = 2 

 

Update a transaction.

 

However, it should be noted that the value of this addition or subtraction must be consistent with the field type, and must be converted manually first.