c++ – Insert data into SQLite3 DB


How is data ( int , long long , double ) sqlite3 to sqlite3 ?

Actually, I managed to figure out how to write values ​​of the string type:

 sqlite3_stmt *stmt;
 sqlite3* db;

 int rc;             // return code
 char *errmsg;       // pointer to an error string
 //open out db

 rc = sqlite3_open(nameDB.c_str(), &db);
 //to answer on our request to open
 char* request_status = 0;

 if (rc != SQLITE_OK) {
     printf("ERROR opening SQLite DB: %s\n", sqlite3_errmsg(db));
     goto out;
 printf("opened SQLite handle successfully.\n");
 //create sql request (create columns)
 statistic_query = "CREATE TABLE IF NOT EXISTS  MY_TABLE(uno, dos, tres)";
 //compiling request  
 sqlite3_prepare_v2(db, statistic_query.c_str(), strlen(statistic_query.c_str()), &stmt, NULL);
 //send sql request to database
 rc = sqlite3_step(stmt);

 //and now create sql request with our data
  statistic_query = "INSERT INTO MY_TABLE(uno, dos, tres) VALUES (string1,sting2, string3);";
  sqlite3_prepare_v2(db, statistic_query.c_str(), strlen(statistic_query.c_str()), &stmt, NULL);

  rc = sqlite3_step(stmt);
         if (rc != SQLITE_DONE)
             printf("ERROR inserting data: %s\n", sqlite3_errmsg(db));
             goto out;

That is, in this way, you can form a string from values ​​of the string type for an sql query.

The question is how to write different values ​​into one row in the database (1 column = int , 2 column long long , 3 column double ).

For writing different types, sqlite has the corresponding functions:

long long: int sqlite3_bind_int64(sqlite3_stmt*, int, long long int);

double: int sqlite3_bind_double(sqlite3_stmt*, int, double);

int: int sqlite3_bind_int(sqlite3_stmt*, int, int);

But it is not very clear to me how to implement my task using these functions. (ps: also the second question, how can the corresponding cell types be set?).


Actually, I figured it out, I found the answer on the official website:


SQL database engines that use rigid typing will usually try to automatically convert values ​​to the appropriate datatype.

Consider this: CREATE TABLE t1 (a INT, b VARCHAR (10));

INSERT INTO t1 (a, b) VALUES ('123', 456);

Rigidly-typed database will convert the string '123' into an integer 123 and the integer 456 into a string '456' prior to doing the insert.

That is, SQLite automatically converts the values ​​as they are written and read into a valid format.

And it really works.

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