1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
|
/*-
* See the file LICENSE for redistribution information.
*
* Copyright (c) 1997, 2013 Oracle and/or its affiliates. All rights reserved.
*
*/
#include "ex_sql_utils.h"
/*
* This example demonstrates how to execute queries.
* Example 1. Single Select.
* Example 2. Using 'WHERE' and 'ORDER BY'.
* Example 3. Using 'GROUP BY'.
* Example 4. Subquery.
* Example 5. SQL function.
*/
/* Example body. */
static int
ex_sql_query(db)
db_handle *db;
{
const char* sql;
/*
* Example 1: Single Select.
* - Select rank and name from table university.
*/
echo_info("1. Single Select");
sql = "\tSELECT rank, name from university;";
exec_sql(db, sql);
/*
* Example 2: Use 'WHERE' and 'ORDER BY' to arrange results
* - Select rank, name and country from table university where
* region is Europe. ORDER by country.
*/
echo_info("2. Using 'WHERE' and 'ORDER BY'");
sql = "\tSELECT rank, country, name \n"
"\tFROM university \n"
"\tWHERE region = 'Europe' \n"
"\tORDER BY country;";
exec_sql(db, sql);
/*
* Example 3: Using 'Group by'.
*/
echo_info("3. Group by");
sql = "\tSELECT region, count(*) from university \n"
"\tGROUP BY region \n"
"\tORDER BY region";
exec_sql(db, sql);
/*
* Example 4 Subquery
* - Select rank, name and country from table university where
* country's fullname is 'USA'.
*/
echo_info("4. Subquery");
sql = "\tSELECT rank, country, name from university \n"
"\tWHERE country = (SELECT abbr from country \n"
"\t\t\tWHERE country = 'USA');";
exec_sql(db, sql);
/*
* Example 5: SQL functions
* - Output current system date.
*/
echo_info("5. SQL functions: Echo current date");
sql = "\tSELECT date('now');";
exec_sql(db, sql);
return 0;
}
int
main()
{
db_handle *db;
/* Setup environment and preload data. */
db = setup("./ex_sql_query.db");
load_table_from_file(db, university_sample_data, 1/* Silent */);
load_table_from_file(db, country_sample_data, 1/* Silent */);
/* Run example. */
ex_sql_query(db);
/* End. */
cleanup(db);
return 0;
}
|
