Android 删除带有多个子句的where子句的SQLite行
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Delete SQLite Row with where clause with multiple clauses
提问by Gareth Bowen
I've been searching around and not managed to find a solution or working example so here goes.
我一直在四处寻找，但没有找到解决方案或工作示例，所以这里是。
I've set up an SQLite database which has five columns with different fields which effectively builds a list for the user. There will be multiple values in the list that are the same, save for the ROWID which is set to auto increment.
我已经建立了一个 SQLite 数据库，它有五列不同的字段，可以有效地为用户构建一个列表。列表中会有多个相同的值，除了设置为自动递增的 ROWID。
Neither the user nor the program will know the ROWID once a value has been entered into the database, so I want for the user to be able to remove one row if it contains all four of the other fields.
一旦将值输入到数据库中，用户和程序都不会知道 ROWID，因此我希望用户能够删除包含所有四个其他字段的一行。
My code looks like this:
我的代码如下所示：
Database
.delete(DATABASE_TABLE,
"KEY_DATE='date' AND KEY_GRADE='style2' AND KEY_STYLE='style' AND KEY_PUMPLEVEL='pumpLevel'",
null);
But this does not remove any values. I'm almost certain that the syntax of this command is to blame.
但这不会删除任何值。我几乎可以肯定这个命令的语法是罪魁祸首。
How do I format a where clause for delete command with multiple where clauses?
如何使用多个 where 子句格式化 delete 命令的 where 子句？
Solution from below:
从下面的解决方案：
ourDatabase.delete(DATABASE_TABLE, "ROWID = (SELECT Max(ROWID) FROM "
+ DATABASE_TABLE + " WHERE " + "date=? AND grade=? AND "
+ "style=? AND pump_level=?)", new String[] { date, grade,
style, pumpLevel });
回答by Sam
I have a feeling that KEY_DATE, KEY_GRADE, etc are you Java variable names notyour actual column names. Try changing your code to this:
我有一种感觉KEY_DATE，KEY_GRADE, 等是您的 Java 变量名，而不是您的实际列名。尝试将您的代码更改为：
.delete(DATABASE_TABLE,
KEY_DATE + "='date' AND " + KEY_GRADE + "='style2' AND " +
KEY_STYLE + "='style' AND " + KEY_PUMPLEVEL + "='pumpLevel'",
null);
Also I assume that 'date', 'style', etc are stored in local variables, you should use the whereArgsparameter to project yourself from SQL Injection Attacks:
此外，我认为'date'，'style'等存储在本地变量，你应该使用的whereArgs参数从Project自己的SQL注入攻击：
.delete(DATABASE_TABLE,
KEY_DATE + "=? AND " + KEY_GRADE + "=? AND " +
KEY_STYLE + "=? AND " + KEY_PUMPLEVEL + "=?",
new String[] {date, grade, style, pumpLevel});
(where date = "date", grade = "style2", etc)
（其中date = "date"，grade = "style2"等）
Added from comments
从评论中添加
To delete the last row use this:
要删除最后一行，请使用：
.delete(DATABASE_TABLE,
"ROWID = (SELECT Max(ROWID) FROM " + DATABASE_TABLE + ")",
null);
To delete your last matching row try this:
要删除最后一个匹配的行，试试这个：
.delete(DATABASE_TABLE,
"ROWID = (SELECT Max(ROWID) FROM " + DATABASE_TABLE + " WHERE " +
"KEY_DATE='date' AND KEY_GRADE='style2' AND " +
"KEY_STYLE='style' AND KEY_PUMPLEVEL='pumpLevel')",
null);
But see my second note about SQL Injection Attacks to protect your data.
但是请参阅我关于 SQL 注入攻击以保护您的数据的第二个说明。
回答by Diego Torres Milano
You should use:
你应该使用：
Database.delete(DATABASE_TABLE,
"KEY_DATE=? AND KEY_GRADE = ? AND KEY_STYLE = ? AND KEY_PUMPLEVEL = ?",
new String[]{"date", "style2", "style", "pumpLevel"});
which simplifies escaping values.
这简化了转义值。
