feat(multiple_rows): initial commit

multiple_rows/main.c

@@ -0,0 +1,65 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <libpq-fe.h>
+
+void do_exit(PGconn *conn) {
+  PQfinish(conn);
+  exit(1);
+}
+
+int main(int argc, char **argv) {
+  /*declaration*/
+  const char *conninfo;
+  
+  printf("main() Started...\n");
+
+  /*read command line*/
+  if (argc > 1){
+    printf("main() argv[1]: %s\n", argv[1]);
+    conninfo = argv[1];
+  }else{
+    printf("call ./main <connection info>\n");
+    return 1;
+  }
+
+  /*connect to database*/
+  PGconn *conn = PQconnectdb(conninfo);
+
+  if (PQstatus(conn) == CONNECTION_BAD) {
+    fprintf(stderr, "Connection to database failed: %s\n",
+            PQerrorMessage(conn));
+    do_exit(conn);
+  }else if(PQstatus(conn)==CONNECTION_OK){
+    printf("main() connected to database\n");
+  }else{
+    printf("main() connection status NOT known\n");
+  }
+
+  char *user = PQuser(conn);
+  char *db_name = PQdb(conn);
+  char *pswd = PQpass(conn);
+  printf("User: %s\n", user);
+  printf("Database name: %s\n", db_name);
+  printf("Password: %s\n", pswd);
+
+  /*retrive server of database using SQL statement*/
+  /*PGRES_TUPLS_OK is returned for a query that returns data*/
+  PGresult *res = PQexec(conn, "SELECT * FROM entities");
+  if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+    printf("No data retrieved\n");
+    PQclear(res);
+    do_exit(conn);
+  }
+
+  /*return the number of rows in the query result*/
+  int rows = PQntuples(res);
+
+  for(int i=0; i<rows; i++){
+    printf("%s %s \n", PQgetvalue(res,i,0),
+	   PQgetvalue(res,i,1));
+  }
+  PQclear(res);
+
+  PQfinish(conn);
+  return 0;
+}

multiple_rows/makefile

@@ -0,0 +1,24 @@
+# Docu
+#
+#$@ is the name of the file to be made
+#$? is the names of the changed dependents
+#$< the name of the related file that caused the action
+#$* the prefix shared by target and dependent files
+#
+# Others
+RM      = /bin/rm -f
+#
+# Source, Executable, Includes, Library Defines
+EXE    = main
+#
+# Compiler, Linker Defines
+CC      = /usr/bin/gcc
+#
+all: main.o
+	$(CC) main.c -I/usr/include/postgresql -L/usr/lib/x86_64-linux-gnu -lpq -std=c99 -Wall -o $(EXE)
+#
+main.o:
+	$(CC) -c main.c -I/usr/include/postgresql
+# Clean Up Objects, Exectuables, Dumps out of source directory
+clean:
+	$(RM) *.o $(EXE) *~

multiple_rows/readme.md

@@ -0,0 +1,23 @@
+* build
+
+```
+make
+```
+
+* run
+
+```
+./main 'postgresql://<user>:<secret>@<hostname>:<port>/<db>'
+```
+
+* or run
+
+```
+./main 'postgresql://<user>:<secret>@<hostname>:<port>/<db>'
+```
+
+* or run
+
+```
+./main "host=<hostname> port=<port> user=<user> password=<<secret>> dbname=<db>"
+```