[nacknic]

fixed!

#include <amxmodx>
#include <sqlx>
 
new Handle:SQL_Tuple
new Handle:SQL_Connection 
public plugin_init() {
	register_clcmd( "say /getusers", "sql_con" )
}
public sql_con(id) {
    if(!(get_user_flags(id) & ADMIN_KICK)) return client_print(0,print_chat,"you have no access")
    SQL_Tuple = SQL_MakeDbTuple("00.000.000.000","root","","test",120) //not show my ip
    new err, error[256]
    SQL_Connection = SQL_Connect(SQL_Tuple, err, error, charsmax(error)) 
    if(SQL_Connection == Empty_Handle) client_print(0,print_chat,"%s",error)
    else sql_select(id)
}
public sql_select(id){
    client_print(0,print_chat,"connect to db")
    new ip[21] 
    new user[21]
    get_user_ip(id,ip,charsmax(ip),1)
    new Handle:query = SQL_PrepareQuery(SQL_Connection,"SELECT username FROM `clients` WHERE `ip`= '%s'",ip)
    if(SQL_Execute(query)) {
    	if(SQL_NumResults(query) > 0) {
		new columNumOfUsername = SQL_FieldNameToNum(query,"username")
		if(columNumOfUsername >= 0) {
			SQL_ReadResult(query,columNumOfUsername,user,charsmax(user))
			client_print(0,print_chat,"%s",user)
		} else client_print(0,print_chat,"cant find username column")
	} else client_print(0,print_chat,"not fount results")
    } else client_print(0,print_chat,"cant execute the query")
    SQL_FreeHandle(SQL_Connection)	
}

if i have more results (more then one row with same ip)

#include <amxmodx>
#include <sqlx>
 
new Handle:SQL_Tuple
new Handle:SQL_Connection 
public plugin_init() {
	register_clcmd( "say /getusers", "sql_con" )
}
public sql_con(id) {
    if(!(get_user_flags(id) & ADMIN_KICK)) return client_print(0,print_chat,"you have no access")
    SQL_Tuple = SQL_MakeDbTuple("00.000.000","root","","test",120) 
    new err, error[256]
    SQL_Connection = SQL_Connect(SQL_Tuple, err, error, charsmax(error)) 
    if(SQL_Connection == Empty_Handle) client_print(0,print_chat,"%s",error)
    else sql_select(id)
}
public sql_select(id){
    client_print(0,print_chat,"connect to db")
    new ip[21] 
    new user[21][21]
    get_user_ip(id,ip,charsmax(ip),1)
    new q[] = "SELECT username FROM `test`.`clients` WHERE `ip`= '%s';"
    new Handle:query = SQL_PrepareQuery(SQL_Connection,q,ip)
    if(SQL_Execute(query)) {
    	new howManyRowsReturned = SQL_NumResults(query)
    	if(howManyRowsReturned  > 0) {
		client_print(0,print_chat," found %d users:",howManyRowsReturned)
		new columNumOfUsername = SQL_FieldNameToNum(query,"username")
		if(columNumOfUsername >= 0) {
			for(new i=0; i<howManyRowsReturned; i++) {
				SQL_ReadResult(query,columNumOfUsername,user,charsmax(user))
				client_print(0,print_chat,"client # %d = %s",i+1,user)
				SQL_NextRow(query)
			}
		} else client_print(0,print_chat,"cant find username column")
	} else client_print(0,print_chat,"not fount results")
    } else client_print(0,print_chat,"cant execute the query")
    SQL_FreeHandle(SQL_Connection)	
}

see pic database:
https://ibb.co/NTKSBh7