chore: refactore

create_table/main.c

@@ -22,7 +22,7 @@ int main(int argc, char **argv) {
     printf("main() argv[1]: %s\n", argv[1]);
     conninfo = argv[1];
   }else{
-    printf("call ./main <connection info>\n");
+    fprintf(stderr, "Usage: %s <connection info>\n", argv[0]);
     return 1;
   }
 

multiple_rows/main.c

@@ -18,8 +18,8 @@ int main(int argc, char **argv) {
     printf("main() argv[1]: %s\n", argv[1]);
     conninfo = argv[1];
   }else{
-    printf("call ./main <connection info>\n");
-    return 1;
+    fprintf(stderr, "Usage: %s <connection info>\n", argv[0]);
+    exit(1);
   }
 
   /*connect to database*/

multiple_rows/readme.md

@@ -1,23 +1,19 @@
-* build
+* install dependencies on Debian Bullseye
+```
+sudo apt install libpq-dev --no-install-recommends
+```
 
+* build
 ```
 make
 ```
 
 * run
-
 ```
-./main 'postgresql://begerad:secret@localhost:5432/sib00_vbn_gtfs'
+./main 'postgresql://<user>:<secret>@<host>:<port>/<database>'
 ```
 
 * or run
-
 ```
-./main 'postgresql://begerad:secret@localhost:5432/vbn_data'
+./main "host=<host> port=<port> user=<user> password=<<secret>> dbname=<database>"
 ```
-
-* or run
-
-```
-./main "host=localhost port=5432 user=begerad password=<secret> dbname=vbn_data"
-```

prepared_statement/main.c

@@ -15,7 +15,7 @@ int main(int argc, char *argv[]) {
 
   printf("main() Started...\n");
   if (argc != 3) {
-    fprintf(stderr, "Usage: ./main <row id> <connection info>\n");
+    fprintf(stderr, "Usage: %s <row id> <connection info>\n", argv[0]);
     exit(1);
   }
 
@@ -63,6 +63,7 @@ int main(int argc, char *argv[]) {
     printf("main() connection status NOT known\n");
   }
 
+  /*SQL statement*/
   char *stm = "SELECT * FROM cars_cleanup WHERE Id=$1";
 
   /*create prepared statement*/

simple_query/main.c

@@ -18,7 +18,7 @@ int main(int argc, char **argv) {
     printf("main() argv[1]: %s\n", argv[1]);
     conninfo = argv[1];
   }else{
-    printf("call ./main <connection info>\n");
+    fprintf(stderr, "Usage: %s <connection info>\n", argv[0]);
     return 1;
   }