1>DatabaseClass.obj : error LNK2019: unresolved external symbol _mysql_real_connect@32 referenced in function "public: __thiscall C4::DatabaseClass::DatabaseClass(void)" (??0DatabaseClass@C4@@QAE@XZ)
1>DatabaseClass.obj : error LNK2019: unresolved external symbol _mysql_init@4 referenced in function "public: __thiscall C4::DatabaseClass::DatabaseClass(void)" (??0DatabaseClass@C4@@QAE@XZ)
1>DatabaseClass.obj : error LNK2019: unresolved external symbol _mysql_close@4 referenced in function "public: virtual __thiscall C4::DatabaseClass::~DatabaseClass(void)" (??1DatabaseClass@C4@@UAE@XZ)
MySQL and linker errors
Author
Okay, I give up.
I have the MySQL libraries (5.1) downloaded and a database all set up.
I added (to my C++ program)
#include <my_global.h>
#include <mysql.h>
to my database class. I added
libmysql.lib
to my project options (along with setting up the library and include directories).
The compiler is finding the .h files. It is finding the library files okay. But I'm still getting linker errors:
Anyone have any ideas what is wrong? Searching the web seems to indicate I have performed all the needed steps. I even tried adding a couple extra libs (mysqlclient.lib, zlib.lib) to no effect. I guess I must have missed something though.
Oddly, if I do an internal file search within the lib directory (where all the sql lib files live) for "mysql_init" (for instance), it comes up with 0 matches. The same search in the include folder comes up with matches as expected. Could I have bad .lib files?
If you're building a 32-bit project, are you using the 32-bit MySQL connector?
Similarly, if it's a 64-bit project, the 64-bit connector?
You could try dumping the lib's symbols using
dumpbin /exports libmysql.lib
Similarly, if it's a 64-bit project, the 64-bit connector?
You could try dumping the lib's symbols using
dumpbin /exports libmysql.lib
Author
Yes, I believe I have the right connector package.
This is a dump of the file. I notice it does not have the @32 or @4 on the end of the exported function names. Is that my problem? How would I go about fixing that?
This is a dump of the file. I notice it does not have the @32 or @4 on the end of the exported function names. Is that my problem? How would I go about fixing that?
Dump of file e:\dc\trunk\update server\code\mysql\lib\debug\libmysql.libFile Type: LIBRARY Exports ordinal name _dig_vec_lower _dig_vec_upper bmove_upp client_errors delete_dynamic free_defaults get_defaults_options getopt_compare_strings getopt_ull_limit_value handle_options init_dynamic_array insert_dynamic int2str is_prefix list_add list_delete load_defaults modify_defaults_file my_end my_getopt_print_errors my_init my_malloc my_memdup my_no_flags_free my_path my_print_help my_print_variables my_realloc my_strdup myodbc_remove_escape mysql_affected_rows mysql_autocommit mysql_change_user mysql_character_set_name mysql_close mysql_commit mysql_data_seek mysql_debug mysql_disable_reads_from_master mysql_disable_rpl_parse mysql_dump_debug_info mysql_embedded mysql_enable_reads_from_master mysql_enable_rpl_parse mysql_eof mysql_errno mysql_error mysql_escape_string mysql_fetch_field mysql_fetch_field_direct mysql_fetch_fields mysql_fetch_lengths mysql_fetch_row mysql_field_count mysql_field_seek mysql_field_tell mysql_free_result mysql_get_character_set_info mysql_get_client_info mysql_get_client_version mysql_get_host_info mysql_get_parameters mysql_get_proto_info mysql_get_server_info mysql_get_server_version mysql_get_ssl_cipher mysql_hex_string mysql_info mysql_init mysql_insert_id mysql_kill mysql_list_dbs mysql_list_fields mysql_list_processes mysql_list_tables mysql_master_query mysql_more_results mysql_next_result mysql_num_fields mysql_num_rows mysql_options mysql_ping mysql_query mysql_read_query_result mysql_real_connect mysql_real_escape_string mysql_real_query mysql_refresh mysql_rollback mysql_row_seek mysql_row_tell mysql_rpl_parse_enabled mysql_rpl_probe mysql_rpl_query_type mysql_select_db mysql_send_query mysql_server_end mysql_server_init mysql_set_character_set mysql_set_local_infile_default mysql_set_local_infile_handler mysql_set_server_option mysql_shutdown mysql_slave_query mysql_sqlstate mysql_ssl_set mysql_stat mysql_stmt_affected_rows mysql_stmt_attr_get mysql_stmt_attr_set mysql_stmt_bind_param mysql_stmt_bind_result mysql_stmt_close mysql_stmt_data_seek mysql_stmt_errno mysql_stmt_error mysql_stmt_execute mysql_stmt_fetch mysql_stmt_fetch_column mysql_stmt_field_count mysql_stmt_free_result mysql_stmt_init mysql_stmt_insert_id mysql_stmt_num_rows mysql_stmt_param_count mysql_stmt_param_metadata mysql_stmt_prepare mysql_stmt_reset mysql_stmt_result_metadata mysql_stmt_row_seek mysql_stmt_row_tell mysql_stmt_send_long_data mysql_stmt_sqlstate mysql_stmt_store_result mysql_store_result mysql_thread_end mysql_thread_id mysql_thread_init mysql_thread_safe mysql_use_result mysql_warning_count set_dynamic strcend strcont strdup_root strfill strinstr strmake strmov strxmov Summary C9 .debug$S 14 .idata$2 14 .idata$3 8 .idata$4 8 .idata$5 E .idata$6
Author
Oops, you were right mattd. I had the wrong connector. I DLed the 64 bit connector (because I have a 64 bit OS), but my application is a 32 bit app. I switched over to the 32 bit connector files and everything linked fine.
Thanks for pointing me in the right direction.
Thanks for pointing me in the right direction.
Ah good, I was stumped and was going to post some drastic stabs in the dark :)
EDIT: Those _blah@4 names are the result of __stdcall name mangling, in case you were wondering.
EDIT: Those _blah@4 names are the result of __stdcall name mangling, in case you were wondering.
Author
Okay, I'll try not to keep asking questions about this, but I have one more. I'm stumped on why I'm not getting a connection to my database.
I created my database. I use Toad to connect, so I know it's working (I even created a table within Toad, then checked that it was there in the database using the command line client. They are definitely connected, so that is working).
But in my program, I can't connect.
Obviously, I'm going to change my login details in this post, but I'll keep it consistent. Here is the constructor for the databse class, which is responsible for connecting to the database
This returns the error: "Can't connect to MySQL server on 'localhost' (10061)"
However, in Toad, I connect just fine using the same login
Connection Type: TCP
Host: localhost
User: MyUserName
Password: MyPassword
Database: MyDatabase
Port: 3306
Any ideas?
I created my database. I use Toad to connect, so I know it's working (I even created a table within Toad, then checked that it was there in the database using the command line client. They are definitely connected, so that is working).
But in my program, I can't connect.
Obviously, I'm going to change my login details in this post, but I'll keep it consistent. Here is the constructor for the databse class, which is responsible for connecting to the database
DatabaseClass::DatabaseClass() { mysql = mysql_init(NULL); if (mysql_real_connect(mysql, "localhost", "MyUserName", "MyPassword", "MyDatabase", 3306, NULL, 0) == NULL) { Connection = false; Error = mysql_error(mysql); } else Connection = true; }This returns the error: "Can't connect to MySQL server on 'localhost' (10061)"
However, in Toad, I connect just fine using the same login
Connection Type: TCP
Host: localhost
User: MyUserName
Password: MyPassword
Database: MyDatabase
Port: 3306
Any ideas?
Author
Well, I got it, though I don't really understand why it was failing.
I changed "localhost" to "127.0.0.1" and it connected fine. I don't know why the original was not working though. I don't like things I don't understand, heh. But I guess I'll let it go, since it now works.
I changed "localhost" to "127.0.0.1" and it connected fine. I don't know why the original was not working though. I don't like things I don't understand, heh. But I guess I'll let it go, since it now works.
Maybe because of this:
It does sound like it should fallback to TCP, but who knows.
Quote:
If host is NULL or the string "localhost", a connection to the local host is assumed. For Windows, the client connects using a shared-memory connection, if the server has shared-memory connections enabled. Otherwise, TCP/IP is used.
It does sound like it should fallback to TCP, but who knows.
This topic is closed to new replies.
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