SQLite3 question: accessing by column instead of index?
Post: #1
I have written some code to access variables from a table, so I do something like the following...
However I would like to do something like this...
Obviously the code doesnt work, but I want to 1) write my SQL query so I dont have to list all of the tables in the field. 2) I dont want to have to access the fields by column index, I want to access them by column name.
Is this possible in SQLite?
Code:
const char *sql = "SELECT v1, v2, v3 WHERE pk=1";
sqlite3_prepare_v2(database, sql, -1, &init_statement, NULL);
self.myV1 = sqlite3_column_int(init_statement, 0);
self.myV2 = sqlite3_column_int(init_statement, 1);
self.myV3 = sqlite3_column_int(init_statement, 2);However I would like to do something like this...
Code:
const char *sql = "SELECT * WHERE pk=1";
sqlite3_prepare_v2(database, sql, -1, &init_statement, NULL);
self.myV3 = sqlite3_column_int(init_statement, "v3");
self.myV1 = sqlite3_column_int(init_statement, "v1");
self.myV2 = sqlite3_column_int(init_statement, "v2");Obviously the code doesnt work, but I want to 1) write my SQL query so I dont have to list all of the tables in the field. 2) I dont want to have to access the fields by column index, I want to access them by column name.
Is this possible in SQLite?
Post: #2
yes, backwards from what you are expecting:
Code:
int sqlite3_column_count(sqlite3_stmt *pStmt);
const char *sqlite3_column_name(sqlite3_stmt*, int N);
Post: #3
so would i have to do something like this then?
This wouldn't be very efficient , there has to be a better way. Am I missing something?
Code:
int num_fields = sqlite3_column_count(init_statement);
for(index = 0; 0 < num_fields; index++)
{
const char* field_name = sqlite3_column_name(init_statement, index);
if ([@"v1" compare: [NSString stringWithUTF8String:field_name]] == 0)
{
self.myV1 = sqlite3_column_int(init_statement, index);
}
else if ([@"v2" compare: [NSString stringWithUTF8String:field_name]] == 0)
{
self.myV2 = sqlite3_column_int(init_statement, index);
}
else if ([@"v3" compare: [NSString stringWithUTF8String:field_name]] == 0)
{
self.myV3 = sqlite3_column_int(init_statement, index);
}
}This wouldn't be very efficient , there has to be a better way. Am I missing something?
Post: #4
you can store the column indices directly after you prepare the statement, there's no need to do the expensive work during execution.
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