if I have the following two tables
should the primary key of the employee information table select the employee information ID or the employee job number? How to choose the primary key of the growth table? Should the external key of the employee information table choose the employee"s job number or growth ID??
Don"t tell me the answer, I want to know why, thank you guys. Just learned the database
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$selectTip = $pdo->query("SELECT * FROM `tips_rate` WHERE `tip_id` = ".$row[ id ]." " ); $selecttotal = mysqli_num_rows($selectTip); $rate = $pdo->query("SELEC...
for example, the isolation level of transaction An is repeatable read my understanding is that a read sql statement of transaction An is the same as the result repeated many times, regardless of whether or not other transactions have changed the data ...
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do a check-in function `create_time` decimal(20,3) NOT NULL, `create_date_ymd` varchar(15) NOT NULL COMMENT , `create_date_ym` varchar(15) NOT NULL, `create_date_y` int(4) NOT NULL, `create_date_m` int(2) NOT NULL, `create_date_d` int(2) ...
as shown in the following figure the current time is 16 41 00. I want to take this section of data every two hours. How should sql write ? ...
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I want to optimize a sentence about group by. I don t know where to start. I want to find a train of thought . SELECT adv_id, network_id, SUM(re_click) AS clk, SUM(deny_click) AS dny_clk, SUM(re_conver) AS re_ins, SUM(mat_conver) AS mat_ins, SUM(def_...
background: 1. I am a java programmer 2. Recently interviewed for a senior development position 3. The previous project mainly used less oracle,mysql, and the companies interviewed basically used mysql s 4. I am weak in the database 5. Recently, I...
like this SELECT * FROM material WHERE {key:value} limit 1 ...
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check-in table: fields include user id userid check-in time signtime timestamp type int check-in type type is divided into 0 and 1 for check-in and check-out, respectively. A user can sign twice a day, once check-in and one check-out. Check-in and ch...
Table structure ...
use mybatis to configure custom secondary cache. Using xml annotation can use < cache type= "com.test.dao.MybatisRedisCache " > to successfully use custom cache, but using @ CacheNamespace (implementation = MybatisRedisCache.class) on the dao i...
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mybatis+mysql for java projects int batchAmount = 20000; for (int startIndex = 0; startIndex < size; startIndex += batchAmount) { int endIndex = startIndex + batchAmount; endIndex = (endIndex &...
Master and Slave built by mysql5.6, the newly created table is not backed up to the slave library master and slvae data can both correspond to can t the test library be automatically backed up to the slave library when establishing a master-slav...
I want to do a circular sequence to output pictures. Don t know how to write this code? Table structure for example, now the field ID of key=1 is 1, 2, 5, 7, 10, 11, 6 fields I want to output one at a time in order. output id 1 field for t...
for example, if the database has a field type of enum ( axiomagementific database ), can you change this field to enum when there are millions of data in the database? will it be slow? ...
ask God to help me translate this native SQL statement into TP5 thank you! It is Db:: ( name )-> this kind of chained operation select a.id, a.titlerect a. Createwriting time as answer_count from fa_question a. Isometric solvepaper count (b.qid) as ...