1 00:00:00,330 --> 00:00:01,230 Hello, dear friends. 2 00:00:02,210 --> 00:00:07,940 So in this section, we will learn about Ezekial transaction to manage transactions. 3 00:00:07,970 --> 00:00:13,190 We're going to use three commands roll back command, commit command. 4 00:00:13,550 --> 00:00:16,910 And lastly, the Save Point Command. 5 00:00:17,780 --> 00:00:22,100 Our transaction is a unit of work that is performed against a database. 6 00:00:23,080 --> 00:00:28,390 Transactions or units or sequences of work accomplished in a logical order. 7 00:00:29,240 --> 00:00:35,060 Whether in a manual fashion by a user or automatically by some sort of database program. 8 00:00:36,610 --> 00:00:44,620 A transaction is the propagation of one or more changes to the database, for example, if you're creating 9 00:00:44,620 --> 00:00:52,060 a record or updating a record or the leading a record from the table, then you are performing a transaction 10 00:00:52,060 --> 00:00:52,840 on that table. 11 00:00:53,380 --> 00:01:00,130 So logically, it's important to be able to control these transactions in order to ensure the data integrity 12 00:01:00,580 --> 00:01:03,430 as well as to handle database errors. 13 00:01:03,640 --> 00:01:10,570 Practically, you will club many actual queries into a group and you will execute all of them together 14 00:01:10,570 --> 00:01:12,190 as part of a transaction. 15 00:01:13,620 --> 00:01:18,870 All right, so let's assume that you have an account with a thousand dollar balance at a bank and you 16 00:01:18,870 --> 00:01:22,640 want to buy a product on the Internet with your phone, is that's what you. 17 00:01:24,680 --> 00:01:26,330 If the process fails. 18 00:01:28,010 --> 00:01:31,790 As soon as you accepted, the bank will not decrease your balance. 19 00:01:34,630 --> 00:01:42,070 Unlike it would wait until the process has been completed, so the bank decreases your balance as soon 20 00:01:42,070 --> 00:01:48,790 as you accept the sale and if something goes wrong with paying to the website or whatever, then even 21 00:01:48,790 --> 00:01:53,280 though the bank decreases your balance, your product will not be sent to you. 22 00:01:53,300 --> 00:01:53,860 Do you understand? 23 00:01:53,890 --> 00:01:58,060 So they'll still take the money and you're not going to get nothing for it. 24 00:01:58,920 --> 00:02:02,420 Because it seems like you didn't pay on the website. 25 00:02:02,430 --> 00:02:03,900 That's what it looks like. 26 00:02:05,570 --> 00:02:08,310 No product, but lower bank balance. 27 00:02:09,110 --> 00:02:10,300 Big problem, yeah. 28 00:02:11,810 --> 00:02:16,370 So the ask all transactions are here to solve this problem. 29 00:02:18,630 --> 00:02:26,190 In general, a transaction is a single unit of work that consists of multiple related tasks that should 30 00:02:26,190 --> 00:02:30,190 succeed or fail as one atomic unit. 31 00:02:31,050 --> 00:02:31,410 All right. 32 00:02:31,710 --> 00:02:38,100 So as soon as you accept the sale, the bank will wait until the process has been fully completed. 33 00:02:38,670 --> 00:02:42,270 That way, if the process failed, the bank will cancel the process. 34 00:02:45,190 --> 00:02:51,520 If the process end successfully, the bank will accept the payment and then decrease your balance so 35 00:02:51,820 --> 00:02:54,220 you'll be able to receive your product. 36 00:02:55,450 --> 00:02:56,080 Acid. 37 00:02:57,920 --> 00:03:01,610 Now, to our understanding, the concept of the rescue server transaction. 38 00:03:03,060 --> 00:03:08,070 I can now describe to you the transaction using the four acid properties. 39 00:03:09,020 --> 00:03:19,520 Now, Acid is an acronym, not an acronym, but an acronym for Adam Midcity, Consistency. 40 00:03:20,360 --> 00:03:22,640 Isolation and durability. 41 00:03:24,470 --> 00:03:25,480 I'll explain it further. 42 00:03:26,640 --> 00:03:35,460 Adam Midcity means that the transaction will succeed as one unit if all the separate tasks succeed with 43 00:03:35,460 --> 00:03:36,090 no issue. 44 00:03:37,360 --> 00:03:43,060 And on the other hand, the failure of any single task within this transaction leads to the overall 45 00:03:43,060 --> 00:03:45,520 transaction failure and rolled back. 46 00:03:46,220 --> 00:03:52,540 So in other words, atomistic guarantees that the transaction is all or nothing. 47 00:03:54,050 --> 00:03:54,890 Consistency. 48 00:03:55,940 --> 00:04:02,750 Guarantees that the transaction will not affect the database consistency and will leave it in a valid 49 00:04:02,750 --> 00:04:10,820 state by complying with all database rules such as foreign keys and constraints defined on the columns 50 00:04:11,810 --> 00:04:16,010 and simple words, only valid data is saved. 51 00:04:19,090 --> 00:04:27,670 Isolation means that each transaction has its own boundary, it's separate from all the other currently 52 00:04:27,670 --> 00:04:33,340 executing transactions and will not be affected by these transactions operations. 53 00:04:34,530 --> 00:04:38,010 In other words, transactions don't affect each other. 54 00:04:39,740 --> 00:04:40,670 Durability. 55 00:04:44,060 --> 00:04:50,390 Durability means that the result of the committed transaction that is written permanently to the database 56 00:04:50,780 --> 00:04:57,440 will not be lost even in the case of an abnormal system, failure or termination. 57 00:04:58,600 --> 00:05:04,180 As there should be a mechanism of recovering this data that we're going to see later on in the next 58 00:05:04,180 --> 00:05:10,540 coming articles of the series, but in other words, written data will not be lost. 59 00:05:13,530 --> 00:05:14,700 Transaction state. 60 00:05:16,440 --> 00:05:19,800 The state of the transaction can be summarized as. 61 00:05:21,260 --> 00:05:25,640 The running transaction is referred to as the active transaction. 62 00:05:27,660 --> 00:05:34,110 So the transaction does not complete its execution, it's referred to as a failed transaction that is 63 00:05:34,110 --> 00:05:36,270 aborted without being committed. 64 00:05:37,370 --> 00:05:39,950 So that just means that the process will be canceled. 65 00:05:40,860 --> 00:05:47,250 The transaction that is not fully committed yet is referred to as a partially committed transaction. 66 00:05:48,190 --> 00:05:53,680 If the partially committed transaction completes its execution successfully, it will then be committed, 67 00:05:54,250 --> 00:05:57,580 otherwise it will be failed, then aborted. 68 00:05:58,300 --> 00:06:03,940 The transaction that completes its execution successfully without any error is referred to as a committed 69 00:06:04,090 --> 00:06:04,870 transaction. 70 00:06:06,190 --> 00:06:09,490 So on this situation, the process will be saved successfully.