How to access MySQL database through C language in Linux

Error message: Can

Error message: Can

Error message: Can't connect to local MySQL server through socket '/var/run/mysqld. sock'

Solution: Create a mysqld directory under/var/run/, and create a link pointing to:/opt/lampp/var/mysql. sock

Input command: ln-s/opt/lampp/var/mysql. sock/var/run/mysqld. sock

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The main. c file program code is as follows:

// ================================================ ======================================

# Include
# Include
# Include

Main ()
{
Char dbhost [32], dbuser [16], dbpasswd [16], dbname [16];
Char query [256];
Int count;
MYSQL * mysql;/* indicates the handle to a database connection */
MYSQL_RES * mysql_res;/* indicates the result of a query in the returned row */
MYSQL_ROW mysql_row;/* string array */
MYSQL_FIELD * field;
My_ulonglong rows;
Int I, num_fields;
/* This type is used for row numbers, mysql_affected_rows (), mysql_num_rows (), and mysql_insert_id ()
**/

Sprintf (dbhost, "localhost ");
Sprintf (dbuser, "root ");
Sprintf (dbpasswd, "123456 ");
Sprintf (dbname, "system ");

If (! (Mysql = mysql_init (NULL)/* obtain or initialize a MYSQL structure */
{
Printf ("mysql_init failed! ");
Mysql_close (mysql );
Exit (0 );
}

If (! Mysql_real_connect (mysql, dbhost, dbuser, dbpasswd, dbname, 3306, NULL, 0 ))
{/* Connect to a MySQL Server */
Printf ("% s", mysql_error (mysql ));
Printf ("\ n failed to connect to the server. Please contact the system administrator! \ N ");
Mysql_close (mysql );
Exit (0 );
}

Strcpy (query, "select * from ns_materiel_import where status = 0 order by itemid asc limit 1000 ");
If (mysql_query (mysql, query)/* execute an SQL query specified as an empty string */
{
Printf ("% s", mysql_error (mysql ));
Printf ("\ nmysql_query error! \ N ");
Mysql_close (mysql );
Exit (0 );
}
Mysql_res = mysql_store_result (mysql);/* retrieve a complete set of results for the customer */
Rows = mysql_num_rows (mysql_res);/* returns the number of duplicate columns in a result set */
If (rows = 0)/* This Management Code does not exist and returns */
{
Printf ("\ n return value is blank \ n ");
Mysql_free_result (mysql_res);/* release the memory used by a result set */
Mysql_close (mysql);/* close a server connection */
Exit (0 );
}
Else
{
Num_fields = mysql_num_fields (mysql_res );
For (I = 0; I <num_fields; I ++)/* print the field name */
{
Field = mysql_fetch_field_direct (mysql_res, I );
Printf ("% s \ t", field-> name );
}


For (count = 0; count {
Mysql_row = mysql_fetch_row (mysql_res);/* obtain the next row from the result set */
For (I = 0; I <num_fields; I ++)
{
Printf ("% s \ t", mysql_row [I]);
}
Printf ("\ n ");
}

}

# If 0
For (count = 0; count {
Mysql_row = mysql_fetch_row (mysql_res);/* obtain the next row from the result set */
Printf ("User ID: % s \ t", mysql_row [0]);
Printf ("username: % s \ t", mysql_row [2]);
Printf ("Real name: % s \ t", mysql_row [4]);
Printf ("nickname: % s \ t", mysql_row [5]);
Printf ("title: % s \ t", mysql_row [7]);
Printf ("Tel: % s \ n", mysql_row [8]);
}
# Endif

Mysql_free_result (mysql_res );
Mysql_close (mysql );
Printf ("\ nApp exit !!! \ N ");
}

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The contents of Makefile are as follows:

#===================================================== ======================================
# Makefile template write by albert. shi
#
# Shanghai
#===================================================== ======================================

# Standard defines:
CC = gcc

WRES = windres

Hopem =/usr/src/linux-2.6.32.21
VPATH = $ (hopem)/include
ODir =.
Bin =.
Src =.
LibDirs =
IncDirs =

LIBS =-s-rdynamic-L/usr/lib/mysql-lmysqlclient
C_FLAGS + =-I/usr/include/mysql/-DBIG_JOINS = 1-fno-strict-aliasing-DUNIV_LINUX-Wl,-Bsymbolic-functions

# C_FLAGS =-O-I/usr/include/mysql-DBIG_JOINS = 1-fno-strict-aliasing-DUNIV_LINUX-Wl, -Bsymbolic-functions-rdynamic-L/usr/lib/mysql-lmysqlclient

SRCS = \
$ (Src)/main. c \
# $ (Src)/getfileargv. c \
# $ (Src)/bdidll. c \
# $ (Src)/bdisetup. c

EXOBJS = \
$ (ODir)/main. o \
# $ (ODir)/getfileargv. o \
# $ (ODir)/bdidll. o \
# $ (ODir)/bdisetup. o

ALLOBJS = $ (EXOBJS)
ALLBIN = $ (Bin)/app
ALLTGT = $ (Bin)/app

# User defines:

### Targets follow ---------------------------------

All: $ (ALLTGT)

Objs: $ (ALLOBJS)

Cleanobjs:
Rm-f $ (ALLOBJS)

Cleanbin:
Rm-f $ (ALLBIN)

Cleantgt:
Rm-f $ (ALLTGT)

Clean: cleanobjs cleanbin

Cleanall: cleanobjs cleanbin cleantgt

### User Targets follow ---------------------------------

### Dependency rules follow -----------------------------
# --- List all bin file ----------------------------------
$ (ALLTGT): $ (EXOBJS)
$ (CC)-o $ (ALLBIN) $ (EXOBJS) $ (incDirs) $ (libDirs) $ (LIBS)

#--------------------------------------------------------
# ---- Compile all *. c to *. c ------
%. O: %. c
$ (CC) $ (C_FLAGS) $ (incDirs)-c-o $ @ $ <

# --- Another way to compile *. c to *. o ------
# $ (ODir)/main. o: main. c
# $ (CC) $ (C_FLAGS) $ (incDirs)-c-o $ @ $ <

#--------------------------------------------------------

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