Simple SQL Lite table/import question

问题:

I have a simple SQL question. I want to make a 3 column database and I have the following code:

sqlite3 meshdb.db "create table t1 (t1key INTEGER PRIMARY KEY, prideID, pubmedID);"

When I try to import a simple csv file with two columns (prideID and pubmedID), I get a "expected 3 columns of data but found 2" error. I want the t1key to be an integer, and automatically count up as new fields are added. Do I have to put NOT NULL in front of PRIMARY KEY to for this to work?

回答1:

.import does not support reshaping the input (except from setting the separator). You need to import the CSV file into a temporary table and the insert that into the real table. Here is a example session:

$ cat a.csv 
1,2
3,4
5,6
$ sqlite3 a.db
SQLite version 3.6.23.1
Enter ".help" for instructions
Enter SQL statements terminated with a ";"
sqlite> create table foo(id integer primary key,x,y);
sqlite> create temp table footmp(x,y);
sqlite> .separator ,
sqlite> .import a.csv footmp
sqlite> select * from footmp;
1,2
3,4
5,6
sqlite> insert into foo(x,y) select * from footmp; 
sqlite> select * from foo; 
1,1,2
2,3,4
3,5,6
sqlite> drop table footmp; 

You see that ID is counted up. This is because a column with type INTEGER PRIMARY KEY is treated as an alias for the internal ROWID - which always is a unique, ascending number.

回答2:

Instead of insert use

create table newtable as select  * from  footmp;

It is better and quicker.

回答3:

With the .version of sqlite (SQLite 3.7.15.2 2013-01-09) I'm on, you don't have to import into a temp table first. All I did was to make sure I set a separator before starting the import. I did specify the id values for each row, so, my first column in the csv was a set of unique integers