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我必须将时间戳值插入表中。我通过编写存储过程来插入值。
这是我的存储过程的代码。

CREATE OR REPLACE FUNCTION dataInsert_Schedule() RETURNS boolean As
$$
DECLARE
    i integer;
    j integer;
    dur integer;
    tup Channel%rowtype;
BEGIN
    FOR tup IN SELECT * FROM Channel
    LOOP
        for i in 0..6 LOOP --days
            for j in 0..23 LOOP  --hours
                dur = round((random() * 2) + 1);
                IF i + dur > 24 then
                    dur = 24 - i;
                END IF;
                INSERT INTO Schedule VALUES(tup.Channel_ID, round((random() * 999) + 1),( current_date + (integer to_char(i,'9')) )+ (interval to_char(j,'99') || ' hour'), (interval  dur ||' hour'));
                i = i + dur - 1;
            END LOOP;
        END LOOP;
    END LOOP;
    return true;
END
$$ LANGUAGE plpgsql;

当我编写查询时Select * From dataInsert_Schedule();,出现以下错误:

ERROR:  syntax error at or near "to_char"
LINE 1: ...d((random() * 999) + 1),( current_date + (integer to_char( $...
                                                             ^
QUERY:  INSERT INTO Schedule VALUES( $1 , round((random() * 999) + 1),( current_date + (integer to_char( $2 ,'9')) )+ (interval to_char( $3 ,'99') || ' hour'), (interval  $4  ||' hour'))
CONTEXT:  SQL statement in PL/PgSQL function "datainsert_schedule" near line 15

********** Error **********

ERROR: syntax error at or near "to_char"
SQL state: 42601
Context: SQL statement in PL/PgSQL function "datainsert_schedule" near line 15

我第一次尝试这个

INSERT INTO Schedule VALUES(tup.Channel_ID, round((random() * 999) + 1),( current_date + (integer ''||i) )+ (interval (j ||' hour')), (interval dur ||' hour'));

插入方式,但我遇到了同样的错误。

为什么我收到此错误?

schedule表定义如下:

CREATE TABLE Schedule(
Channel_ID Integer  REFERENCES Channel(Channel_ID),
Program_ID Integer  REFERENCES Program(Program_ID),
Start_Time Timestamp NOT NULL,
Duration Interval NOT NULL,
CONSTRAINT Schedule_Key PRIMARY KEY(Channel_ID, Program_ID)
);
4

2 回答 2

1

它对我有用:

select (to_char(1,'99') || ' hour')::interval;

你不需要to_char

select (1 || ' hour')::interval;
 interval 
----------
 01:00:00

所以就是这样:

INSERT INTO Schedule
VALUES (
tup.Channel_ID,
round((random() * 999) + 1),
(current_date + i::integer) + (j || ' hour')::interval,
(dur ||' hour')::interval
)
于 2012-11-07T14:51:19.520 回答
0

可以在字符串常量之前指定类型名称以将其转换为该类型,但它仅适用于常量。所以integer '123'很好但integer to_char(something)interval column_name不允许,这就是您的查询失败的原因。

这在手册的 SQL 语法章节中进行了解释,特别是本段:其他类型的常量
摘抄:

可以使用以下任何一种表示法输入任意类型的常量:

type 'string'
'string'::type
CAST ('string' AS type )

及以下:

::、CAST() 和函数调用语法也可用于指定任意表达式的运行时类型转换

与问题相关的一点是type 'string'符号不包含在可以接受任意表达式的语法中,与::and相反cast()

于 2012-11-07T18:39:22.000 回答