Thanks for the clarification. I'll need to study the docs on the three part method and slowly figure it out. A working example sure would be nice! -- Al
On Mon, 26 Jul 2004 11:21:08 +0100 (BST), Christian Smith <[EMAIL PROTECTED]> wrote: > Typed data retrieval is not supported by the callback method of execution. > > You must use the prepare/step/finalize execution method. > > Check out: > http://www.sqlite.org/capi3.html > > in particular, the sqlite3_step and related functions in section 2.2 > "Executing SQL statements." This section gives the functions to retrieve > typed data from a row. > > Sorry, no sample code as I've yet to dive headlong into v3 yet. My work > for the moment is v2 only. > > Christian > > > > On Sun, 25 Jul 2004, Al Danial wrote: > > >Since SQLite v2 was 'typeless', one had to call atoi() and atof() on terms > >of the array *azArg to convert the text strings returned by a query into > >integers and doubles. > > > >As I understand it SQLite v3 stores integers and doubles in their native > >binary format so one should be able to get at the numeric data without > >text string conversions via atoi()/atof(). Does anyone have C code that > >demonstrates how this could be done? > > > >Here's a sample database and corresponding query + callback I'm currently > >using: > > > > create table people ( name text, age integer , lat float, lon float ); > > insert into people values ( 'Alice' , 43 , 1.1 , -3.4e-3 ); > > insert into people values ( 'Bob' , 28 , 5.5 , -3.1e+3 ); > > insert into people values ( 'Cindy' , 21 , 8.8 , 3.2e+5 ); > > > >The query: > > > > rc = sqlite3_exec_printf(sql_db, > > "select * from people order by age asc " > > , a1_i1_d2_cb, > > &sql_data, > > &zErrMsg); > > > >The callback: > > > > int a1_i1_d2_cb(void *pArg, int nFields, char **azArg, char **azCol) { > > /* return array of [string, integer, double, double] */ > > callback_data *p = (callback_data*) pArg; > > > > if (!azArg) > > return 0; > > strncpy(p->a[p->nRows][0], azArg[0], SQL_STR_SIZE); > > p->i[p->nRows][0] = atoi(azArg[1]); > > p->x[p->nRows][0] = atof(azArg[2]); > > p->x[p->nRows][1] = atof(azArg[3]); > > ++(p->row_index); > > ++(p->nRows); > > > > return 0; > > } > > > >The callback variable 'sql_data' has type 'callback_data' defined like this: > > > > #define SQL_BLOCK_SIZE 1000 > > #define SQL_STR_SIZE 200 > > #define SQL_MAX_COLUMNS 20 > > > > typedef struct { > > sqlite3 *db; /* database handle */ > > FILE *out; /* output file handle */ > > char nullvalue[SQL_MAX_COLUMNS]; /* string to display for NULL's */ > > char zDbFilename[SQL_STR_SIZE]; /* db filename */ > > int nRows; /* size of a[]/i[]/x[] with valid data */ > > int row_index; /* pointer to current row within table */ > > char a[SQL_BLOCK_SIZE][SQL_MAX_COLUMNS][SQL_STR_SIZE];/* string */ > > int i[SQL_BLOCK_SIZE][SQL_MAX_COLUMNS]; /* integer */ > > double x[SQL_BLOCK_SIZE][SQL_MAX_COLUMNS]; /* double */ > > } callback_data; > > > >My questions: > > How can I populate sql_data.i[] and sql_data.x[] without calling atoi() > > and atof() on terms of azArg[]? > > Is there example C code out there that demonstrates the technique? > > -- Al > > > > -- > /"\ > \ / ASCII RIBBON CAMPAIGN - AGAINST HTML MAIL > X - AGAINST MS ATTACHMENTS > / \ >
