Re: Nested queries

#1

Quote:

Query query = con.query();
ResUse res = query.use("SELECT id,value FROM table");
while

Shouldn't there be a ; at the end of your first query?

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#2

On Fri, Oct 21, 2005 at 12:34:36PM +0200, Mattias Fliesberg wrote:

Quote:

while (Row row = res.fetch_row()) {
string stuff;
string id = (row.at(0)).c_str();
string value = (row.at(1)).c_str();
Query query_0 = con.query();
ResUse res_0 = query_0.use("SELECT value2 FROM table2 WHERE id=" + id);
Row row_0 = res_0.fetch_row();
string value2 = (row_0.at(0)).c_str();
if (value2.length() > 0)
stuff = value2;
else
stuff = value;
/* ... */
}

It dies at "query_0.use(..." with this output from gdb:

#0 0x401e7467 in std::basic_string<char, std::char_traits<char>,
std::allocator<char> >::~basic_string ()
from /usr/lib/libstdc++.so.5
#1 0x08052bd3 in ~basic_stringbuf (this=0xbffff5d0) at query.h:195
#2 0x08058aeb in ~Query (this=0xbffff580) at main.cpp:45
#3 0x0805837d in main (argc=1, argv=0xbffffd54) at main.cpp:76

Is there an exception being thrown? I'm not sure how it can get into the
destructors at the query_0.use() point.

- Chris

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#3

Mattias Fliesberg wrote:

Quote:

I'm trying to execute a query, within another queries loop.

The MySQL C API that underlies MySQL++ imposes restrictions on that.
RTFM. You must consume all rows from a SELECT before you can issue
another query on the same connection.

To get around this, you can use separate Connection objects, and get a
Query object from each one.

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#4

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aW9uIHNvbHV0aW9uIGJ1dCBpdCBkaWRuJ3QKd29yaywgZ3Vlc3 MgSSdsbCB0cnkgaXQgYWdhaW4u
CgovL01hdHRpYXMKCgpPbiAxMC8yMy8wNSwgV2FycmVuIFlvdW 5nIDxteXNxbHBwQGV0ci11c2Eu
Y29tPiB3cm90ZToKPiBNYXR0aWFzIEZsaWVzYmVyZyB3cm90ZT oKPiA+Cj4gPiBJJ20gdHJ5aW5n
IHRvIGV4ZWN1dGUgYSBxdWVyeSwgd2l0aGluIGFub3RoZXIgcX VlcmllcyBsb29wLgo+Cj4gVGhl
IE15U1FMIEMgQVBJIHRoYXQgdW5kZXJsaWVzIE15U1FMKysgaW 1wb3NlcyByZXN0cmljdGlvbnMg
b24gdGhhdC4KPiBSVEZNLiAgWW91IG11c3QgY29uc3VtZSBhbG wgcm93cyBmcm9tIGEgU0VMRUNU
IGJlZm9yZSB5b3UgY2FuIGlzc3VlCj4gYW5vdGhlciBxdWVyeS BvbiB0aGUgc2FtZSBjb25uZWN0
aW9uLgo+Cj4gVG8gZ2V0IGFyb3VuZCB0aGlzLCB5b3UgY2FuIH VzZSBzZXBhcmF0ZSBDb25uZWN0
aW9uIG9iamVjdHMsIGFuZCBnZXQgYQo+IFF1ZXJ5IG9iamVjdC Bmcm9tIGVhY2ggb25lLgo+Cj4g
LS0KPiBNeVNRTCsrIE1haWxpbmcgTGlzdAo+IEZvciBsaXN0IG FyY2hpdmVzOiBodHRwOi8vbGlz
dHMubXlzcWwuY29tL3BsdXNwbHVzCj4gVG8gdW5zdWJzY3JpYm U6ICAgIGh0dHA6Ly9saXN0cy5t
eXNxbC5jb20vcGx1c3BsdXM/dW5zdWI9bWF0dGlhcy5mbGllc2JlcmdAZ21haWwuY29tCj4KPg o=

#5

You could use the query.store() call instead of query.use()... this returns
a Result object instead of a ResUse, storing the results in memory all
at once, just like PHP's mysql_query().

See the docs:
http://tangentsoft.net/mysql++/doc/u...html#id2810307

- Chris

On Mon, Oct 24, 2005 at 11:14:59AM +0200, Mattias Fliesberg wrote:

Quote:

Oh, of course it does. But how is it solved in PHP?
I know you can do it there...

I've tried the seperate connection solution but it didn't
work, guess I'll try it again.

//Mattias

On 10/23/05, Warren Young <mysqlpp (AT) etr-usa (DOT) com> wrote:
Mattias Fliesberg wrote:

I'm trying to execute a query, within another queries loop.

The MySQL C API that underlies MySQL++ imposes restrictions on that.
RTFM. You must consume all rows from a SELECT before you can issue
another query on the same connection.

To get around this, you can use separate Connection objects, and get a
Query object from each one.

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Re: Nested queries

mailing.database.mysql-plusplus mailing.database.mysql-plusplus

Re: Nested queries - 10-21-2005 , 08:51 AM

Re: Nested queries - 10-21-2005 , 09:12 AM

Re: Nested queries - 10-22-2005 , 11:51 PM

Re: Nested queries - 10-24-2005 , 04:15 AM

Re: Nested queries - 10-24-2005 , 05:52 AM