qu.1

来自「linux 下用c++ 开发的一个小型数据库系统」· 1 代码 · 共 50 行

/*
 * test 1 tests QU_Select without indices
 */


/* create relations */
create table soaps(soapid int, name char(28), network char(4), rating real);
load table soaps from ("../data/soaps.data");

create table stars(starid int, real_name char(20), plays char(12), soapid int);
load table stars from ("../data/stars.data");

/*
 * various selections without indices
 */

/* simple selection (should be the same as just printing the relation) */
select soapid, name, network, rating from soaps;
print table soaps;

/* names, ratings, and networks of soaps on NBC */
select name, rating, network from soaps where network = "NBC";

/* print character name, real name, and ids of stars with id's < 12 */
select plays, real_name, starid from stars where starid < 12;

/* ratings, networks, and names of soaps with ratings of 5 or greater */
select rating, network, name from soaps where rating >= 5.0;

/* selection that doesn't find anything */
select real_name, starid from stars where starid > 567;

/* select into a non-existent relation */
select network, soapid, name into ned
from soaps
where network = "CBS";
print table ned;

/* select into a existing relation */
select network, soapid, name into ned
from soaps
where network = "NBC";
print table ned;

/* select into a relation with strings of different sizes */
create table ted (plays char(12), soapid int);
select plays, soapid into ted from stars where plays < "L";
print table ted;