1.47. SQLite-C *

发布时间 ： 2025-10-25 13:32:42 UTC      

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1.47.1. Installation

We need to make sure that the SQLite library is already available on the machine before we use SQLite in the CumberCraft + program. You can check the SQLite installation section to learn about the installation process.

1.47.2. Candlespace + interface API

Here are the important Candlestick + / SQLite interface programs that can meet your needs of using SQLite databases in the Cmax Cure + program. If you need more details, please check the SQLite official documentation.

Serial number

API & description

1

** sqlite3_open(const char filename, sqlite3 * PpDb) * *

This routine opens a connection to the SQLite database file and returns a database connection object for other SQLite programs.

If the filename parameter is NULL or’: memory:’, then sqlite3_open() An in-memory database will be created in RAM, which will only last for the duration of the session.

If the file name filename is not NULL, then sqlite3_open() This parameter value will be used to try to open the database file. If a file with that name does not exist, `` sqlite3_open () `` creates a new database file with that name and opens it.

2

** sqlite3_exec(sqlite3*, const char sql, sqlite_callback, void *data, char * Errmsg) * *

This routine provides a shortcut to execute the SQL command, which is provided by the sql parameter and can consist of multiple SQL commands.

Here, the first parameter sqlite3 is the open database object, sqlite_ callback is a callback, data is its first parameter, and errmsg will be returned to get any errors generated by the program.

sqlite3_exec() The program parses and executes each command given by the sql parameter until the string ends or an error is encountered.

3

sqlite3_close(sqlite3*)

Called before the routine closes sqlite3_open() Open database connection. All connection-related statements should be completed before the connection is closed.

If the query has not been completed, sqlite3_close () ``will return ``SQLITE_BUSY An error message that disables closing.

1.47.3. Connect to the database

The following C code snippet shows how to connect to an existing database. If the database does not exist, it will be created and a database object will be returned.

#include 
#include 

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));
      exit(0);
   }else{
      fprintf(stderr, "Opened database successfully\n");
   }
   sqlite3_close(db);
}
   
 Now, let’s compile and run the above program to create our database in the current directory  test.db  . You can change the path as needed. 
 
 
 
$gcc test.c -l sqlite3
$./a.out
Opened database successfully

 
 
 
 If you want to use C++ source code, you can compile the code as follows: 
 
 
 
$g++ test.c -l sqlite3

 
 
 
 Here, link our program   sqlite3   Library to provide the necessary functions to the C program. This will create a database file in your directory   test.db   You will get the following results: 
 
 
 
-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

 
 
  
 
  1.47.4.  Create a tabl  
 
 The following C code snippet will be used to create a table in the previously created database: 
 
 
 
#include 
#include 
#include 

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
   int i;
   for(i=0; i   
 When the above program is compiled and executed, it will be specified in the   test.db   Create in the file   COMPANY   Table, the final file list is as follows: 
 
 
 
-rwxr-xr-x. 1 root root 9567 May  8 02:31 a.out
-rw-r--r--. 1 root root 1207 May  8 02:31 test.c
-rw-r--r--. 1 root root 3072 May  8 02:31 test.db

 
 
  
 
  1.47.5.  INSERT operation  
 
 The following C code snippet shows how to create the   COMPANY   Create a record in the table: 
 
 
 
#include 
#include 
#include 

static int callback(void *NotUsed, int argc, char **argv, char **azColName){
   int i;
   for(i=0; i   
 When the above program is compiled and executed, it will be specified in the   COMPANY   The given record is created in the table and the following two rows are displayed: 
 
 
 
Opened database successfully
Records created successfully

 
 
  
 
  1.47.6.  SELECT operation  
 
 Before we start talking about examples of getting records, let’s take a look at some of the details of the callback function, which will be used in our example. This callback provides a message from the   SELECT   Statement to get the result. It declares as follows: 
 
 
 
typedef int (*sqlite3_callback)(
void*,    /* Data provided in the 4th argument of sqlite3_exec() */
int,      /* The number of columns in row */
char**,   /* An array of strings representing fields in the row */
char**    /* An array of strings representing column names */
);

 
 
 
 If the above callback is in   sqlite_exec()   As the third parameter in the program, then   SQLite   Will be   SQL   Each execution within the parameter   SELECT   Each record processed in the statement calls this callback function. 
 
 The following C code snippet shows how to create the   COMPANY   Get and display records in the table: 
 
 
 
#include 
#include 
#include 

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for(i=0; i   
 When the above program is compiled and executed, it produces the following results: 
 
 
 
Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 20000.0

Callback function called: ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

 
 
  
 
  1.47.7.  UPDATE operation  
 
 The following C code snippet shows how to use the   UPDATE   Statement to update any records, and then from the   COMPANY   Table to get and display updated records: 
 
 
 
#include 
#include 
#include 

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for(i=0; i   
 When the above program is compiled and executed, it produces the following results: 
 
 
 
Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 25000.0

Callback function called: ID = 2
NAME = Allen
AGE = 25
ADDRESS = Texas
SALARY = 15000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

 
 
  
 
  1.47.8.  DELETE operation  
 
 The following C code snippet shows how to use the   DELETE   Statement to delete any records, and then from the   COMPANY   Get and display the remaining records in the table: 
 
 
 
#include 
#include 
#include 

static int callback(void *data, int argc, char **argv, char **azColName){
   int i;
   fprintf(stderr, "%s: ", (const char*)data);
   for(i=0; i   
 When the above program is compiled and executed, it produces the following results: 
 
 
 
Opened database successfully
Callback function called: ID = 1
NAME = Paul
AGE = 32
ADDRESS = California
SALARY = 20000.0

Callback function called: ID = 3
NAME = Teddy
AGE = 23
ADDRESS = Norway
SALARY = 20000.0

Callback function called: ID = 4
NAME = Mark
AGE = 25
ADDRESS = Rich-Mond
SALARY = 65000.0

Operation done successfully

 
 
   
                    
                
                

                    

                        

                            
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                            1.47. SQLite-C * 
                        

                    

                

            
        
        

            

    
        

            

                

                    
                        
                        
                            
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