Update
An update expression that updates the data values of the fields in the table, where you can set a specific conditional expression, and records that match the conditional expressions are updated.
The syntax is as follows:
UPDATE table
New value for SET field
WHERE condition Expression
You need an update expression when you want to update multiple records at the same time, or when you update records in more than one table.
You can update the data values of multiple fields at the same time, for example, the following example will be all records in the product table, price 90 percent, freight 70 percent:
UPDATE Product
SET Price = Price * 0.9, freight = freight * 0.7
An update expression does not produce a recordset. When you update a record with an update expression, the original value cannot be restored. Therefore, if you want to know which records will be updated, it is recommended that you use Select and the same where condition expressions to query the results, to determine which records you want to update, and then to update the record by performing an update expression.
Of course you can copy the data at any time, in case you update the wrong records with an update expression, you can still save the records from your backup.
Let's look at an example of using this SQL instruction in ASP code.
For example, ASP code rs5.asp as follows, [Update product Set quantity = quantity + 10] Use Update to add 10 to the Quantity field data for all records in the product table:
<%
Set conn1 = Server.CreateObject ("ADODB. Connection ")
Conn1. Open "dbq=" & Server.MapPath ("Ntopsamp.mdb") & ";D river={microsoft Access Driver (*.mdb)};D riverid=25;fil=ms Access; "
sql = "Update product Set quantity = quantity + 10"
Set a = conn1. Execute (SQL)
Set RS3 = Server.CreateObject ("ADODB. Recordset ")
sql = "SELECT * from Product order by code"
Rs3. Open sql,conn1,1,1,1
%>
<table colspan=8 cellpadding=5 border=0>
<TR>
<TD align=center bgcolor= "#800000" ><font color= "#FFFFFF" > Code </FONT></TD>
<TD align=center bgcolor= "#800000" ><font color= "#FFFFFF" > Name </FONT></TD>
<TD align=center bgcolor= "#800000" ><font color= "#FFFFFF" > Price </FONT></TD>
<TD align=center bgcolor= "#800000" ><font color= "#FFFFFF" > Quantity </FONT></TD>
