java 如何在 Apache Derby 中使用 SEQUENCE？
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How to use SEQUENCE in Apache Derby?
提问by Tomasz B?achowicz
I'd like to use SEQUENCE support in Apache Derby 10.7. I've created the sequence with the following statement:
我想在 Apache Derby 10.7 中使用 SEQUENCE 支持。我使用以下语句创建了序列：
CREATE SEQUENCE SAMPLE_SEQ AS INT MAXVALUE 999999 CYCLE;
How can I select next/current value from the SAMPLE_SEQ? Could you please help me out with the query?
如何从 中选择下一个/当前值SAMPLE_SEQ？你能帮我解决这个问题吗？
回答by Andreas Dolk
Apache Derby Doc says: Use a NEXT VALUE FOR expression
Apache Derby Doc 说：使用 NEXT VALUE FOR 表达式
Should be something like
应该是这样的
SELECT NEXT VALUE FOR SAMPLE_SEQ;
回答by a_horse_with_no_name
Use NEXT VALUE FOR as documented in the manual:
按照手册中的说明使用 NEXT VALUE FOR：
http://db.apache.org/derby/docs/10.7/ref/rrefsqljnextvaluefor.html#rrefsqljnextvaluefor
http://db.apache.org/derby/docs/10.7/ref/rrefsqljnextvaluefor.html#rrefsqljnextvaluefor
回答by user611544
To get the current value of the sequence the following SQL should be executed:
要获取序列的当前值，应执行以下 SQL：
SELECT CURRENTVALUE FROM SYS.SYSSEQUENCES WHERE SEQUENCENAME='SAMPLE_SEQ'
回答by sola
In the SQL command prompt, you can query the next value with this statement:
在 SQL 命令提示符下，您可以使用以下语句查询下一个值：
values NEXT VALUE FOR <sequence_name>
This will work as an expression embedded into an INSERT statement. E.g.:
这将用作嵌入到 INSERT 语句中的表达式。例如：
INSERT INTO <table_name> (IDFIELD) VALUES (NEXT VALUE FOR <sequence_name>)
回答by ankurrc
In case you want to fetch the 'current value' from the 'sequence':
如果您想从“序列”中获取“当前值”：
- values ( next value for <sequence> )
- 值（<序列>的下一个值）
Same in Java using JDBC:
在 Java 中使用 JDBC 也是如此：
ResultSet rs = conn.prepareStatement("values (next value for <sequence>)").executeQuery();
rs.next();
int seqValue = rs.getInt(1);
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