Linux C language links mysql examples

Linux - C language links mysql examples

Step 1:

Install mysql, reference: https: / / www ofstack. com article / 39190. htm

Step 2:

Install the mysql.h function library

sudo apt-get install libmysqlclient-dev

After execution, you can see the /usr/include/MySQL directory

Then start our link.

First look at my database

mysql> show databases;
+--------------------+
| Database      |
+--------------------+
| information_schema |
| chat_room     |
| mysql       |
| mysql_shiyan    |
| performance_schema |
| sys        |
+--------------------+
6 rows in set (0.00 sec)
mysql> use chat_room;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> show tables;
+---------------------+
| Tables_in_chat_room |
+---------------------+
| user_message    |
+---------------------+
1 row in set (0.00 sec)
mysql> select * from user_message;
+------+-------+--------+
| ID  | name | passwd |
+------+-------+--------+
|  1 | linux | linux |
|  2 | lyt  | lyt  |
+------+-------+--------+
2 rows in set (0.00 sec)

As you can see, I have the user_message table in the chat_room database, and all we have to do is read out the data in this table.

Direct up code

#include<stdio.h>
#include<stdlib.h>
#include<errno.h>
#include<mysql/mysql.h>

int main(void)
{
  char *sql;
  sql="SELECT * FROM user_message;";
  int res;// perform sql The return flag after the statement 
  MYSQL_RES *res_ptr;// A pointer to the query result 
  MYSQL_FIELD *field;// Field structure pointer 
  MYSQL_ROW result_row;// Returns the query information by row 
  int row,column;// The number of rows and columns returned by the query 
  MYSQL *conn;//1 Two database link Pointers 
  int i,j;

  // Initializes the connection handle 
  conn = mysql_init(NULL);

  if(conn == NULL) { // If the return NULL Indicates that initialization failed 
    printf("mysql_init failed!\n");
    return EXIT_FAILURE;
  }

  // Make the actual connection 
  // parameter conn Connection handle, host　mysql Host or address ,user The user name ,passwd password ,database_name The database name , The rest is the default 
  conn = mysql_real_connect(conn,"localhost","lyt","","chat_room",0,NULL,0);
  if (conn) {
    printf("Connection success!\n");
  } else {
    printf("Connection failed!\n");
  }
  mysql_query(conn,"set names gbk");// Prevent garbled code. Setup and database encoding 1 There will be no confusion 

  res = mysql_query(conn,sql);// Right back 0
  if(res) {
    perror("my_query");
    mysql_close(conn);
    exit(0);
  } else{
    // Give me the query results res_ptr
    res_ptr = mysql_store_result(conn);
    // If the result is not empty , The output 
    if(res_ptr) {
      column = mysql_num_fields(res_ptr);
      row = mysql_num_rows(res_ptr);
      printf(" To check the %d line \n",row);
      // The field name of the output 
      for(i = 0;field = mysql_fetch_field(res_ptr);i++) {
        printf("%10s",field->name);
      }
      puts("");
      // Output the result by line 
      for(i = 1;i < row+1;i++){
        result_row = mysql_fetch_row(res_ptr);
        for(j = 0;j< column;j++) {
          printf("%10s",result_row[j]);
        }
        puts("");
      }
    }
  }
  // Close the connection before exiting 
  mysql_close(conn);

  return 0;
}

The results of

gcc -o mysql a.c -L/usr/lib/mysql -lmysqlclient
./mysql 
Connection success!
 To check the 2 line 
    ID   name  passwd
     1   linux   linux
     2    lyt    lyt

Notes written quite clearly, what is not clear can give me a message, we 1 piece of learning!