SELECT语句以显示额外的列

Question

Table1

Code | Type | Color | Description |

1 | Fruit | Red | apple

1 | Fruit | Orange | peach

1 | Fruit | Blue | blueberry

1 | Fruit | Green | sour apple

1 | Fruit | Yellow | lemon

I'm running the code below:

SELECT
code,
type,
color,
description
FROM table

If someone sends me a CSV with additional columns is there a code that I can add that produces the string Error in the additional columns fields?

I won't know the additional columns name since it's up to the user to designate it--All I want to produce is the effect that if they did I'll know if there was an additional field added.

Answer 1

The MySQL LOAD DATA command

• Ignores extra columns in the input file and possibly produces a warning if they are found
• Doesn't give names to input file columns; it assigns their values to table columns and variables, which are fixed (either implicit in the tble definition or explicit in the LOAD DATA command)

In other words, you'll always load Code , Type , Color and Description into your table, regardless of input malformations.

There is a possible workaround to find lines with one or more extra columns: load the file into an empty auxiliary table with 5 columns with a NULL default. If any line in the CSV file has 5 or more columns, the test table will contain records in which the fifth column IS NOT NULL ; you can count them.