Ignoring Datafile Columns
Problem
Your datafile contains columns that should be ignored rather than loaded into the table.
Solution
That’s not a problem if the columns are at the ends of the input
lines. Otherwise, you can use a column list with LOAD
DATA
that assigns the columns to be ignored to a dummy user-defined
variable.
Discussion
Extra columns that occur at the end of input lines are easy to
handle. If a line contains more columns than are in the table,
LOAD
DATA
just ignores them (although it might produce
a nonzero warning count).
Skipping columns in the middle of lines is a bit more involved. Suppose that you want to load information from a Unix password file /etc/passwd, which contains lines in the following format:
account:password:UID:GID:GECOS:directory:shell
Suppose also that you don’t want to bother loading the password column. A table to hold the information in the other columns looks like this:
CREATE TABLE passwd ( account CHAR(8), # login name uid INT, # user ID gid INT, # group ID gecos CHAR(60), # name, phone, office, etc. directory CHAR(60), # home directory shell CHAR(60) # command interpreter );
To load the file, we need to specify that the column delimiter
is a colon, which is easily handled with a
FIELDS
clause:
FIELDS TERMINATED BY ':'
However, we must also tell LOAD
DATA
to skip the second field that contains the password. To do this, add a column list in the statement. The list should include the name of each column to be loaded into the table, and a dummy ...
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