SQL update one column from another column

Question

I'm looking for a way to update a SQL column with a portion
of info from another column in the same table.
example of a sql command
UPDATE table1
SET table1.columnname1 = table1.columnname2
FROM table
WHERE blah blah blah
Here's the thing... I only need a portion of the data found
in the source column. I'm not sure how I would do this then.
for example, the database has countries and states combined
into one column like this 'US-DC', 'US-CA', US-FL', etc. I want to
separate these into two columns, a country column and a state
column.... and I dont want to go though all the results and do this
line by line. How would I write the SQL command so that it puts
just the country in the country column, and puts just the state in
the state column, and it omits the dash all together.
any ideas?

Answer 1

It depends. Are you using PHP and mySQL or ASP and SQL?
If you are using mysql and PHP you could use the following
code to loop through all records in your datatbase.
$sql="SELECT * FROM tablename"; //SET tablename to the name
of your database table.
$result=mysql_query($sql)or die(mysql_error(). " - $sql");
for($x = 0; $row=mysql_fetch_assoc($result); $x++){
//set up the variables from the table
$ID=$row['ID']; //this is the primary key
$var1=$row['contrystatecolumn']; //this is the name of the
column which holds the country-state
$var2=explode("-", $var1); //now we explode the string to get
the country and the state seperated and place the results into an
array
$country=$var2[0]; //this is the first piece of the exploded
string in the array
$state=$var2[1]; //this is the second piece of the exploded
string in the array
//now we update the database record with the new information
//remember to replace the tablename with your actual table
name and the columns country and state with the acutal names of
your columns in your table
$sql2="UPDATE tablename SET country='$country'.
state='$state' WHERE ID='$ID'";
$result2=mysql_query($sql2)or die(mysql_error() . " -
$sql2");
This code will loop through every record in your table and do
what you want very quickly.
Hope this helps
Stan Forrest
Senior Web Developer
ATG Internet