MySQL 4.1/5.0

[DJMaze]

As we all know MySQL AB has released 5.0 of it's SQL server.
If you are comming from 4.0 then you would probably have to enhance your coding skills due to more strict rules to be ISO compliant.

NULL, NOT NULL and DEFAULT are much stricter so that a column/field must be identified as so in a INSERT statement. (Read the documents regarding data types and such if you don't understand)

Something else in 5.0.12 and up is the parse error regarding

SELECT * FROM table1 t1, table2 t2 LEFT JOIN table3 t3 ON (t3.field = t1.field)

Because t1.field is NOT accessible since the query is handled as being

SELECT * FROM table1 t1, ( table2 t2 LEFT JOIN table3 t3 ON (t3.field = t1.field) )

Instead your code should be like

SELECT * FROM (table1 t1, table2 t2) LEFT JOIN table3 t3 ON (t3.field = t1.field)

Another issue (which already exists for ages even in 4.0) is the transfer of data in different character sets.
Be shure to use the correct SET NAMES and SET DEFAULT CHARACTER SET especialy now with the utf8/unicode support