c++ - Are the column count and column decltypes invariant for the duration of the execution of a SQLite prepared statement? -

-

when @ code other folks have written using sqlite3 c api, find sqlite3_column_decltype , sqlite3_column_count called inner loop (once per result row).

my understanding of database these values never change if statement re-compiled (see the bit sqlite3_prepare_v2).

so should able call these once , cache them after call sqlite3_prepare.

the columns' declared types can change, if use same statement in 2 transactions , database schema changed between them. in same situation, column count can change, if query using select *.

however, single query execution inside transaction (either manual or automatic one). if cache values after call sqlite3_prepare_v2() , use them until next call sqlite3_reset()/sqlite3_finalize(), fine. can cache them longer if ensure uses inside same transaction.


Comments

Post a Comment

Popular posts from this blog

c++ - llvm function pass ReplaceInstWithInst malloc -

-
#include "llvm/pass.h" #include "llvm/ir/module.h" #include "llvm/ir/function.h" #include "llvm/support/raw_ostream.h" #include "llvm/ir/legacypassmanager.h" #include "llvm/ir/instrtypes.h" #include "llvm/transforms/ipo/passmanagerbuilder.h" #include "llvm/ir/irbuilder.h" #include "llvm/transforms/utils/basicblockutils.h" using namespace llvm; namespace { struct replacepass : public functionpass { static char id; replacepass() : functionpass(id) {} virtual bool runonfunction(function &f) { allocainst* insttoreplace = ??? basicblock::iterator ii(insttoreplace); replaceinstwithinst(insttoreplace->getparent()->getinstlist(), ii, new allocainst(type::int32ty, 0, insttoreplace)); return true; } }; } char replacepass::id = 0; static void registerreplacepass(const passmanagerbuilder &, legacy::passmanagerbase &pm) { pm.add(new re...
Read more

Cross-Compiling Linux Kernel for Raspberry Pi - ${CCPREFIX}gcc -v does not work -

-
i'm trying follow this guide . i'm running both ubuntu 12.04.5 lts (gnu/linux 3.13.0-74-generic x86_64) on "real" hardware , 14.04.1 via virtualbox on mac. problem don't past step 1: hoffmann@angl99:~$ export ccprefix=/home/hoffmann/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf- hoffmann@angl99:~$ ${ccprefix}gcc -v i'm getting following error: -bash: /home/hoffmann/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc: no such file or directory however, file i'm told missing there: hoffmann@angl99:~$ less /home/hoffmann/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc "/home/hoffmann/tools/arm-bcm2708/gcc-linaro-arm-linux-gnueabihf-raspbian/bin/arm-linux-gnueabihf-gcc" may binary file. see anyway? this result of basic error/misconception. suggest solution? thanks! sebastian ok - i've worked out (with of person po...
Read more

java.lang.NoClassDefFoundError When Creating New Android Project -

-
i've tried installing (and re-installing) android studio several times now, , each time, studio isn't able create new android project. when attempt initial android studio window (ie. basic 'create', 'open', 'import' etc options), i'm asked of questions in wizard, brief progress dialog, followed nothing @ all. if open incomplete project process creates choosing 'open' list, can try choosing create new android project menu. this has same issue, error message in output console time... java.lang.noclassdeffounderror: com/sun/xml/internal/bind/v2/model/annotation/annotationreader (wrong name: com/sun/xml/internal/bind/v0/model/qnnotation/annotationreader) note: when installed android studio, installed incompatible jdk (1.8, not 1.7). have had go default project settings change jdk uses 1.8. does know how can avoid this? there place should downloading jxb classes? missing in java paths? this appears have been caused cor...
Read more