truncate

Truncate Table Within Transaction

由 痞子三分冷 提交于 2019-11-27 01:32:26
问题 Can the SQL "truncate table" command be used within a transaction? I am creating an app and my table has a ton of records. I want to delete all the records, but if the app fails I was to rollback my transaction. Deleting each record takes a very long time. I'm wondering if I use truncate table, can I still rollback the transaction and get my data back in the event of a failure. I realize that truncate table doesn't write each delete to the transaction log, but I'm wondering if it writes the

Truncate with condition

由 为君一笑 提交于 2019-11-27 01:13:58
问题 truncate ->this resets the entire table, is there a way via truncate to reset particular records/check conditions. For ex: i want to reset all the data and keep last 30 days inside the table. Thanks. 回答1: No, TRUNCATE is all or nothing. You can do a DELETE FROM <table> WHERE <conditions> but this loses the speed advantages of TRUNCATE . 回答2: The short answer is no : MySQL does not allow you to add a WHERE clause to the TRUNCATE statement. Here's MySQL's documentation about the TRUNCATE

Pros & Cons of TRUNCATE vs DELETE FROM

由 帅比萌擦擦* 提交于 2019-11-27 00:40:19
问题 Could someone give me a quick overview of the pros and cons of using the following two statements: TRUNCATE TABLE dbo.MyTable vs DELETE FROM dbo.MyTable It seems like they both do the same thing when all is said and done; but are there must be differences between the two. 回答1: TRUNCATE doesn't generate any rollback data, which makes it lightning fast. It just deallocates the data pages used by the table. However, if you are in a transaction and want the ability to "undo" this delete, you need

Truncated Data when Importing from Excel to an Access Memo Field

由 我怕爱的太早我们不能终老 提交于 2019-11-26 23:15:30
问题 Access is truncating the data in a couple Memo fields when I am appending an Excel file. The field in the Access table is already set as a Memo type. I believe the problem is that I do not have any entries in the first few rows of some of the memo fields. Access is assuming the data is a text field, even though I have already set it as a Memo type. I have tried appending as a CSV. Did not work. I have put dummy data in the first row that exceeds the 255 character limit and the data is not

SQL Server silently truncates varchar's in stored procedures

由 可紊 提交于 2019-11-26 22:04:34
According to this forum discussion , SQL Server (I'm using 2005 but I gather this also applies to 2000 and 2008) silently truncates any varchar s you specify as stored procedure parameters to the length of the varchar, even if inserting that string directly using an INSERT would actually cause an error. eg. If I create this table: CREATE TABLE testTable( [testStringField] [nvarchar](5) NOT NULL ) then when I execute the following: INSERT INTO testTable(testStringField) VALUES(N'string which is too long') I get an error: String or binary data would be truncated. The statement has been

Truncate Decimal number not Round Off [duplicate]

由 ぃ、小莉子 提交于 2019-11-26 20:24:10
Possible Duplicate: c# - How do I round a decimal value to 2 decimal places (for output on a page) I want to truncate the decimals like below i.e. 2.22939393 -> 2.229 2.22977777 -> 2.229 Bill the Lizard double d = 2.22977777; d = ( (double) ( (int) (d * 1000.0) ) ) / 1000.0 ; Of course, this won't work if you're trying to truncate rounding error, but it should work fine with the values you give in your examples. See the first two answers to this question for details on why it won't work sometimes. You can use Math.Round : decimal rounded = Math.Round(2.22939393, 3); //Returns 2.229 Or you can

Postgresql Truncation speed

由 ぐ巨炮叔叔 提交于 2019-11-26 19:34:27
We're using Postgresql 9.1.4 as our db server. I've been trying to speed up my test suite so I've stared profiling the db a bit to see exactly what's going on. We are using database_cleaner to truncate tables at the end of tests. YES I know transactions are faster, I can't use them in certain circumstances so I'm not concerned with that. What I AM concerned with, is why TRUNCATION takes so long (longer than using DELETE) and why it takes EVEN LONGER on my CI server. Right now, locally (on a Macbook Air) a full test suite takes 28 minutes. Tailing the logs, each time we truncate tables... ie:

Limiting double to 3 decimal places

由 狂风中的少年 提交于 2019-11-26 18:49:06
This i what I am trying to achieve: If a double has more than 3 decimal places, I want to truncate any decimal places beyond the third. (do not round.) Eg.: 12.878999 -> 12.878 If a double has less than 3 decimals, leave unchanged Eg.: 125 -> 125 89.24 -> 89.24 I came across this command: double example = 12.34567; double output = Math.Round(example, 3); But I do not want to round. According to the command posted above, 12.34567 -> 12.346 I want to truncate the value so that it becomes: 12.345 Doubles don't have decimal places - they're not based on decimal digits to start with. You could get

Android: Something better than android:ellipsize=“end” to add “…” to truncated long Strings?

由 柔情痞子 提交于 2019-11-26 18:03:26
问题 This property makes "short and very-long-word" to "short and" . But I want to have smth. like "short and very-lon..." Right now I truncate the String in Java code. However, thats based on the number of characters and not the actual length of the link. So, the result isn't very nice. String title; if(model.getOrganization().length() > 19) { title = model.getText().substring(0, 15).trim() + "…"; } else { title = model.getText(); } ((TextView) findViewById(R.id.TextViewTitle)).setText(title);

How to truncate a foreign key constrained table?

由 |▌冷眼眸甩不掉的悲伤 提交于 2019-11-26 18:02:25
Why doesn't a TRUNCATE on mygroup work? Even though I have ON DELETE CASCADE SET I get: ERROR 1701 (42000): Cannot truncate a table referenced in a foreign key constraint ( mytest . instance , CONSTRAINT instance_ibfk_1 FOREIGN KEY ( GroupID ) REFERENCES mytest . mygroup ( ID )) drop database mytest; create database mytest; use mytest; CREATE TABLE mygroup ( ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY ) ENGINE=InnoDB; CREATE TABLE instance ( ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY, GroupID INT NOT NULL, DateTime DATETIME DEFAULT NULL, FOREIGN KEY (GroupID) REFERENCES mygroup(ID) ON DELETE
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