On 12/14/19 5:22 AM, František Kučera wrote: > Dne 14. 12. 19 v 9:36 Darren Duncan napsal(a): >> With respect to SQLite, every column is the union of: Null, every Integer, >> every Float, every Text, every Blob. > OK, we can close this thread with that it is currently impossible to track > the declared column types through relational operations. > It is currently impossible because it is actually impossible to know the result type of some expressions except by knowing the values and computing it. Some arithmetic operations have thier result type varied based on the value of the result (overflow goes to REAL), a CASE expression can return different types based on the value of an expression, and then you have the fact that NULL has a unique type.
A common issue with computer systems is that when you have something that looks easy to do for a lot of simple cases, but there actually are some cases that are hard or impossible to determine, then those hard cases make it hard to handle the general problem. Thus even without using SQLite's flexibility it types stored in columns, you can't predetermine the type of some expressions. -- Richard Damon _______________________________________________ sqlite-users mailing list sqlite-users@mailinglists.sqlite.org http://mailinglists.sqlite.org/cgi-bin/mailman/listinfo/sqlite-users
