Thank you.
create table if not exists t0 (
h integer primary key autoincrement,
t0info text, unique(t0info));
t0 table allows duplicate t0info column, when in transaction.
how to avoid duplicates for t0info column.
Thanks in advance.
Durga.
On Thu, Jan 12, 2012 at 3:37 PM, Simon Slavin <slav...@bigfraud.org> wrote:
>
> On 12 Jan 2012, at 6:05am, Durga D wrote:
>
> > Insertion time, I am able to get the rowid from
> > sqlite3_last_insert_rowid();
> >
> > It's working fine.
> >
> > Now, t0info record already exists, that time , I should not update
> > with latest rowid. I should fetch the corresponding h value, update in t1
> > table. Here, fetching is the problem:
>
> Yes, this is a problem. If the way your program works may cause it to try
> to insert a t0 row which already exists, you do need at least two SQLite
> commands. The two common structures are ...
>
> create table if not exists t0 (
> h integer primary key autoincrement,
> t0info text);
>
> First option:
>
> INSERT OR IGNORE INTO t0 ...
> SELECT h FROM t0 WHERE ...
>
> Second option:
>
> SELECT h FROM t0 WHERE ...
>
> Then see whether you got 0 or 1 row back. If you got 1 for back, the row
> already exists and you can use that 'h' value. If not, you do the INSERT,
> then use sqlite3_last_insert_rowid().
>
>
>
>
> One option is good if your application structure makes 'IF' commands
> difficult. The other is good if executing SQLite calls slows it down
> unacceptably.
>
> Simon.
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