join

How to make multiple LEFT JOINs with OR fully use a composite index? (part 2)

由 大城市里の小女人 提交于 2020-01-22 04:03:05
问题 It is for a system that calculates how the users scan their fingerprints when they enter/leave the workplace. I don't know how it is called in English. I need to determine if the user is late in the morning, and if the user leaves work early. This tb_scan table contains date and time a user scans a fingerprint. CREATE TABLE `tb_scan` ( `scpercode` varchar(6) DEFAULT NULL, `scyear` varchar(4) DEFAULT NULL, `scmonth` varchar(2) DEFAULT NULL, `scday` varchar(2) DEFAULT NULL, `scscantime`

Django导入静态文件

由 懵懂的女人 提交于 2020-01-22 02:55:49
setting.py: 'DIRS': [os.path. join(BASE_DIR, 'templates'), os.path. join(BASE_DIR, 'static').replace( '\\', '/')], STATIC_ROOT = os.path.join(BASE_DIR, 'static'). replace( '\\', '/') STATICFILES_DIRS = ( ( 'css', os.path. join(STATIC_ROOT, 'css'). replace( '\\', '/')), 　　　　　　　　　　　　( 'images', os.path. join(STATIC_ROOT, 'images'). replace( '\\', '/')), 　　　　　　　　　　　　( 'fonts', os.path. join(STATIC_ROOT, 'fonts'). replace( '\\', '/')), 　　　　　　　　　　　　( 'js', os.path. join(STATIC_ROOT, 'js'). replace( '\\', '/')), ) html: <link href= "/static/css/style.css" rel= "stylesheet" type= "text/css" media=

Difference between inner join and where in select join SQL statement [duplicate]

由 ↘锁芯ラ 提交于 2020-01-21 06:11:05
问题 This question already has answers here : INNER JOIN ON vs WHERE clause (11 answers) Closed 6 years ago . I have two select join SQL statements: select a.id from table_a as a, table_b as b where a.id=b.id; select a.id from table_a as a inner join table_b as b on a.id=b.id; Obviously, they are the same in result. But is there any difference between them , such as performance, portability. 回答1: One difference is that the first option hides the intent by expressing the join condition in the where

Difference between inner join and where in select join SQL statement [duplicate]

由 与世无争的帅哥 提交于 2020-01-21 06:09:45
问题 This question already has answers here : INNER JOIN ON vs WHERE clause (11 answers) Closed 6 years ago . I have two select join SQL statements: select a.id from table_a as a, table_b as b where a.id=b.id; select a.id from table_a as a inner join table_b as b on a.id=b.id; Obviously, they are the same in result. But is there any difference between them , such as performance, portability. 回答1: One difference is that the first option hides the intent by expressing the join condition in the where

How to join unrelated entities with the JPA Criteria API

由 放肆的年华 提交于 2020-01-21 02:40:09
问题 Two database tables have a foreign key relationship. They are mapped to two entities A and B by JPA, but the join columns are manually removed from the entities, so in JPA world classes A and B are not related and you cannot navigate from one to the other through a field/property. Using the JPA Criteria API, is it possible to create a query which joins the two tables? All examples I found on internet uses the join column to achieve the goal, but, as stated above, it was removed from the code

Multiple JOIN FETCH in one JPQL query

由 元气小坏坏 提交于 2020-01-20 16:10:28
问题 I have below entities: public class Category { private Integer id; @OneToMany(mappedBy = "parent") private List<Topic> topics; } public class Topic { private Integer id; @OneToMany(mappedBy = "parent") private List<Posts> posts; @ManyToOne @JoinColumn(name = "id") private Category parent; } public class Post { private Integer id; @ManyToOne @JoinColumn(name = "id") private Topic parent; /* Post fields */ } and I want fetch all categories with joined topics and joined posts using JPQL query. I

Multiple JOIN FETCH in one JPQL query

由 北城以北 提交于 2020-01-20 16:06:39
问题 I have below entities: public class Category { private Integer id; @OneToMany(mappedBy = "parent") private List<Topic> topics; } public class Topic { private Integer id; @OneToMany(mappedBy = "parent") private List<Posts> posts; @ManyToOne @JoinColumn(name = "id") private Category parent; } public class Post { private Integer id; @ManyToOne @JoinColumn(name = "id") private Topic parent; /* Post fields */ } and I want fetch all categories with joined topics and joined posts using JPQL query. I

Multiple JOIN FETCH in one JPQL query

由 自作多情 提交于 2020-01-20 16:04:42
问题 I have below entities: public class Category { private Integer id; @OneToMany(mappedBy = "parent") private List<Topic> topics; } public class Topic { private Integer id; @OneToMany(mappedBy = "parent") private List<Posts> posts; @ManyToOne @JoinColumn(name = "id") private Category parent; } public class Post { private Integer id; @ManyToOne @JoinColumn(name = "id") private Topic parent; /* Post fields */ } and I want fetch all categories with joined topics and joined posts using JPQL query. I

Data from two tables with same column names

由 情到浓时终转凉″ 提交于 2020-01-20 05:18:05
问题 I have a table for users. But when a user makes any changes to their profile, I store them in a temp table until I approve them. The data then is copied over to the live table and deleted from the temp table. What I want to achieve is that when viewing the data in the admin panel, or in the page where the user can double check before submitting, I want to write a single query that will allow me to fetch the data from both tables where the id in both equals $userid. Then I want to display them

Join tables in two databases using SQLAlchemy

由 半腔热情 提交于 2020-01-19 13:04:53
问题 I am working with two MySQL Databases. I want to join a table from DB 1 with a table from DB2 in SQLAlchemy. I am using automap_base while creating data access layer in sqlalchemy as follows... class DBHandleBase(object): def __init__(self, connection_string='mysql+pymysql://root:xxxxxxx@localhost/services', pool_recycle=3600): self.Base_ = automap_base() self.engine_ = create_engine(connection_string, pool_recycle = pool_recycle) self.Base_.prepare(self.engine_, reflect=True) self.session_ =
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