C++ 实现sqilte创建数据库插入、更新、查询、删除
C/C++ Interface APIs
Following are important C/C++ SQLite interface routines, which can suffice your requirement to work with SQLite database from your C/C++ program. If you are looking for a more sophisticated application, then you can look into SQLite official documentation.
| Sr.No. | API & Description |
|---|---|
| 1 |
sqlite3_open(const char *filename, sqlite3 **ppDb) This routine opens a connection to an SQLite database file and returns a database connection object to be used by other SQLite routines. If the filename argument is NULL or ':memory:', sqlite3_open() will create an in-memory database in RAM that lasts only for the duration of the session. If the filename is not NULL, sqlite3_open() attempts to open the database file by using its value. If no file by that name exists, sqlite3_open() will open a new database file by that name. |
| 2 |
sqlite3_exec(sqlite3*, const char *sql, sqlite_callback, void *data, char **errmsg) This routine provides a quick, easy way to execute SQL commands provided by sql argument which can consist of more than one SQL command. Here, the first argument sqlite3 is an open database object, sqlite_callback is a call back for which data is the 1st argument and errmsg will be returned to capture any error raised by the routine. SQLite3_exec() routine parses and executes every command given in the sql argument until it reaches the end of the string or encounters an error. |
| 3 |
sqlite3_close(sqlite3*) This routine closes a database connection previously opened by a call to sqlite3_open(). All prepared statements associated with the connection should be finalized prior to closing the connection. If any queries remain that have not been finalized, sqlite3_close() will return SQLITE_BUSY with the error message Unable to close due to unfinalized statements. |
Connect To Database
Following C code segment shows how to connect to an existing database. If the database does not exist, then it will be created and finally a database object will be returned.
#include <stdio.h>
#include <sqlite3.h>
int main(int argc, char* argv[]) {
sqlite3 *db;
char *zErrMsg = 0;
int rc;
rc = sqlite3_open("test.db", &db);
if( rc ) {
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
return(0);
} else {
fprintf(stderr, "Opened database successfully\n");
}
sqlite3_close(db);
}
Now, let's compile and run the above program to create our database test.db in the current directory. You can change your path as per your requirement.
$gcc test.c -l sqlite3
$./a.out
Opened database successfully
If you are going to use C++ source code, then you can compile your code as follows −
$g++ test.c -l sqlite3
Here, we are linking our program with sqlite3 library to provide required functions to C program. This will create a database file test.db in your directory and you will have the following result.
-rwxr-xr-x. 1 root root 7383 May 8 02:06 a.out -rw-r--r--. 1 root root 323 May 8 02:05 test.c -rw-r--r--. 1 root root 0 May 8 02:06 test.db
Create a Table
Following C code segment will be used to create a table in the previously created database −
#include <stdio.h>
#include <stdlib.h>
#include <sqlite3.h>
static int callback(void *NotUsed, int argc, char **argv, char **azColName) {
int i;
for(i = 0; i<argc; i++) {
printf("%s = %s\n", azColName[i], argv[i] ? argv[i] : "NULL");
}
printf("\n");
return 0;
}
int main(int argc, char* argv[]) {
sqlite3 *db;
char *zErrMsg = 0;
int rc;
char *sql;
/* Open database */
rc = sqlite3_open("test.db", &db);
if( rc ) {
fprintf(stderr, "Can't open database: %s\n", sqlite3_errmsg(db));
return(0);
} else {
fprintf(stdout, "Opened database successfully\n");
}
/* Create SQL statement */
sql = "CREATE TABLE COMPANY(" \
"ID INT PRIMARY KEY NOT NULL," \
"NAME TEXT NOT NULL," \
"AGE INT NOT NULL," \
"ADDRESS CHAR(50)," \
"SALARY REAL );";
/* Execute SQL statement */
rc = sqlite3_exec(db, sql, callback, 0, &zErrMsg);
if( rc != SQLITE_OK ){
fprintf(stderr, "SQL error: %s\n", zErrMsg);
sqlite3_free(zErrMsg);
} else