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update sqltest

07ff322eb6c80cd5e1ce5f5c9aa9d094bd7aaa31 · Ovidiu Constantinescu · Oct 9, 2019 13:42

+87 −22 · 1 file changed

• graph/db/sqltest2.c +87 −22

diff --git a/graph/db/sqltest2.c b/graph/db/sqltest2.c
index 348b5fd..f280ad3 100644
--- a/graph/db/sqltest2.c
+++ b/graph/db/sqltest2.c
@@ -4,9 +4,11 @@
   // Set a glbal string that will hold some SQL sample
   // data
 
-//#define DEBUG
+#define DEBUG 0
+#define MEMWRITE 0
 
-char *sql = "DROP TABLE IF EXISTS Friends;"
+  // sample test data
+char *sSql = "DROP TABLE IF EXISTS Friends;"
             "CREATE TABLE Friends(Id INTEGER PRIMARY KEY, Name TEXT);"
             "INSERT INTO Friends(Name) VALUES ('Tom');"
             "INSERT INTO Friends(Name) VALUES ('Rebecca');"
@@ -14,6 +16,42 @@ char *sql = "DROP TABLE IF EXISTS Friends;"
             "INSERT INTO Friends(Name) VALUES ('Roger');"
             "INSERT INTO Friends(Name) VALUES ('Robert');";
 
+// --------------------------------------------------------------------------------------------------
+
+int dbInsert(sqlite3 *db, char *data) {
+  // Check that a database was passed and we have an open database connection
+  // Note: do not close db connection while sqlite3_exec is running
+  // Note: do not modify the sql statement while sqlite3_exec is running
+  if ( db == NULL ) {
+    fprintf(stderr,"Error with database access, exiting\n");
+    return 1;
+  }
+  char *zErrMsg = NULL;
+  // wrapper function does sqlite3_prepare(),sqlite3_step(), sqlite3_column(), sqlite3_finalize()
+  // 1st arg - an open database
+  // 2nd arg - SQL to be evaluated
+  // 3rd arg - callback function - invoked for each result row comming out of the evaluated statements
+  // int (*callback)(void*, int, char**, char**)
+  // 4th arg - 1st arg to callback function - relaying the argument to it.
+  // 5th arg - error message writte (char **)
+  int rc = sqlite3_exec(db,data,0,0,&zErrMsg);
+  if ( rc != SQLITE_OK ) {
+         fprintf(stderr, "SQL error occured: %s\n", zErrMsg);
+         sqlite3_free(zErrMsg);
+         sqlite3_close(db);
+
+         return 1;
+  }
+
+  return 0;
+}
+
+
+// Select data
+// Update data
+// Delete data
+// --------------------------------------------------------------------------------------------------
+
 int main(int argc, char **argv) {
 
   // 1. Definitions
@@ -26,10 +64,23 @@ int main(int argc, char **argv) {
   int rc;
 
   // This string will hold the english language of the error description
-  char *errmsg;
+  char *zErrMsg;
+
+  // Ensure that the proper arguments are given.`
+  if (argc != 3) {
+      fprintf(stderr, "Usage: %s DATABASE SQL-STATEMENT\n", argv[0]);
+      // Return error code
+      return 1;
+
+  }
 
   // 2. Get the return code from sqlite3_open
+
+#if MEMWRITE == 1
   rc = sqlite3_open(":memory:", &db);
+#else
+  rc = sqlite3_open("sqltest.db", &db);
+#endif
 
   // Test that the return code is OK
   if (rc != SQLITE_OK) {
@@ -41,23 +92,45 @@ int main(int argc, char **argv) {
       // resources associated with the database connection
       // handle should be released by passing it to
       // sqlite3_close() when it is no longer required.
-        sqlite3_close(db);
-        fprintf(stderr,"Database closed.\n");
+      sqlite3_close(db);
+      fprintf(stderr,"Database closed.\n");
 
-            // Return error code
-        return -1;
+     // Return error code
+     return 1;
 
    }
 
-        // Let us know if the database connection was succesfull.
-        printf("Opened database connection succesfully\n");
-
-  //3.Inserting data
-
-#ifdef DEBUG
-  fprintf(stdout,"The SQL statement is: %s\n", sql);
+ // Let us know if the database connection was succesfull.
+ fprintf(stdout,"Opened database connection succesfully\n");
+
+  // Display the SQLite version - debug
+
+#if DEBUG == 1
+  // The sqlite3_stmt represents a single SQL statement
+  sqlite3_stmt *res;
+  // Seeing if the global variable is printed
+  fprintf(stdout,"The SQL statement is: %s\n", sSql);
+  // The sqlite3_prepare is the constructor for the sqlite3_stmt
+  // compile sql text into byte code that will do the work for querying
+  // 1st arg - database connection - obtained  from sqlite3_open()
+  // 2nd arg - zSql - statement to be compiled
+  // 3rd arg - nByte - negative -> read up to the first zero terminator
+  // 4th arg - *ppStmt pointing to a compiled statement that can be run with sqlite3_step()
+  // the calling proc is responsable for deleting the SQL statement with sqlite3_finalize()
+  // 5th arg - pzTail point to the first byte past the end of the first SQL  staement
+  rc = sqlite3_prepare_v2(db, "SELECT SQLITE VERSION()", -1, &res, 0);
+  if (rc == SQLITE_ROW) {
+          fprintf(stdout,"SQLite Version is: %s\n",sqlite3_column_text(res,0));
+  }
 #endif
 
+  // 3.Inserting data - calls dbInsert
+  // 1st arg - open database handle
+  // 2nd arg - string to insert
+  if (!dbInsert(db,sSql) ) {
+        fprintf(stdout,"Inserted data succesfully\n");
+  }
+
 
 
 
@@ -67,11 +140,3 @@ int main(int argc, char **argv) {
   return 0;
 
 }
-
-int dbInsert(db) {
-  int rc = sqlite3_exec(db,sql,0,0,&err_msg)
-
-}
-// Read data
-// Update data
-// Delete data