Sql except apply. Data set operator INTERSECT. Butt of the designer to the data block
nuanxi
I often feed, but for whom is this article? Ale, believe me, don’t make it easy to give replies: from one side, є ninja retailers, which are easy to see, and from the other side - young padovani. But one thing I can say for sure - for the reader, who likes to spell SQL, to add to his rich picture with some more, or even more, details. This article will not have kilometer sides of SQL-backup, a maximum of 1, 2 rows and only those that are rarely seen at my glance. Ale, so like I want to be up to the end, we’ll turn it up, like V z SQL on ty, the article will be tedious. Uсі apply at statti, krіm of the first and fourth can be brought up to the SQL-92 standard.Dani
In order to make life easier for us, I have thrown a simple tablet with tributes, on which those other moments will be tested and for style, I will direct the result of the experiment on them. I check all queries on PostgreSql.Script table with data
CREATE TABLE goods(id bigint NOT NULL, name character varying(127) NOT NULL, description character varying(255) NOT NULL, price numeric(16,2) NOT NULL, article character varying(20) NOT NU , availability boolean NOT NULL , CONSTRAINT pk_goods PRIMARY KEY (id)); INSERT INTO good (id, name, description, price, articul, act_time, availability) VALUES (1, "Slippers", "Soft", 100.00, "TR-75", (ts "2017-01-01 01: 01:01.01"), TRUE); INSERT INTO good (id, name, description, price, articul, act_time, availability) VALUES (2, "Pillow", "Bila", 200.00, "PR-75", (ts "2017-01-02 02:02: 02.02 "), TRUE); INSERT INTO good (id, name, description, price, articul, act_time, availability) VALUES (3, "Kovdra", "Pukhova", 300.00, "ZR-75", (ts "2017-01-03 03:03: 03.03 "), TRUE); INSERT INTO good (id, name, description, price, articul, act_time, availability) VALUES (4, "Pillowcase", "Sira", 400.00, "AR-75", (ts "2017-01-04 04:04: 04.04"), FALSE); INSERT INTO good (id, name, description, price, articul, act_time, availability) VALUES (5, "Prostiradlo", "Shovkova", 500.00, "BR-75", (ts "2017-01-05 05:05: 05.05"), FALSE);
ask
1. Folding feet
І first thing I have є - just food: Chi could b Vi bring the butt of sql-zaputu to vikoristannyam underlings paws? So, not single, subverted?Buttstock
SELECT name "My goods" FROM goods
I've been more than zdivovaniya, if pobachiv tse uppershe. How to try to change paws on single, the result will be absolutely other!
You can get away, but it’s not the same as the butt of a real cut. For me it's not like that. Now I'm actively typing in all my sql-blanks. The bottom line is simple, if you turn through pivroku to sql-data from 40 columns, oh, how ryatuє "our" їhnyu name. Regardless of those that I didn’t say about SQL-92, in the rest of the editorial there is a riddle about the hind legs.
2. Pseudo table. SQL-92
Trohi is not exact, from a glance of terminology, but the essence is simple - a table that is taken as a result of the input in the FROM section. Might be the most important fact in my articlePseudo table
SELECT mock.nickname "Huff", (CASE WHEN mock.huff THEN "Yes" ELSE "Hi" END) "Huff?" FROM (SELECT name AS nickname, availability AS huff FROM goods) mock
The mock application has a pseudo table (also called a virtual table). Obviously, the recognition of the stench is not for the purpose of transforming the right sensation. Such an example.
3. Data block constructor. SQL-92
It sounds scary, just through those that I don’t know good, I’ll translate their interpretation. І how to start on the butt it is easier to explain:Butt of the designer to the data block
SELECT name "Product name", price "Price" FROM (VALUES ("Slippers", 100.00), ("Pillow", 200.00)) AS goods(name, price)
| Іm'ya goods | Price |
| captions | 100.00 |
| Pillow | 200.00 |
Section FROM key word VALUES, for yakim at the temples of tribute, row by row. The bottom line is that we don’t choose data from any tables, but simply create it in bulk, “called” a table, called a column and gave it to the ruling court. This thing turned out to be out of the blue when testing different cases of sql-query, if there are no data for certain tables (your local database), and writing links in insert is sometimes even more foldable, calling for the appearance of tables and borders.
4. Hour, Date and Hour-i-Date
Singingly, skin sticking in requests, with the need to tell the hour, give or give the hour. The literals t, d і ts are accepted by the DBMS in various types. Ale, it’s easier to explain from the butt: For the letters d and t, everything is the same.I'll ask the reader that I'm in Oman, but everything that is said in paragraph 4 is not brought to the SQL language, but is brought to the possibility of forward processing of requests in JDBC.
5. Restriction. SQL-92
We know about the operator NOT However, it is often forgotten that it can be added to a group of predicates like this and to a single column:6. Pairing of data blocks. SQL-92
I'll ask again for the terminology. This is one of my favorite buttsButt of por_vnyannya blok_v danih
SELECT * FROM goods WHERE (name, price, availability) = ("Pillowcase", 400.00, FALSE) - or similar to SELECT * FROM goods WHERE name = "Pillowcase" AND price = 400.00 AND availability = FALSE
As you can see from the butt, the ordering of blocks of data is similar to the ordering of data blocks value_ 1 _block_1 = value_ 1 _block_2, value_ 2 _block_1 = value_ 2 _block_2, value_ 3 _block_1 = value_ 3 _block_2 from victories AND between them.
7. Operators matching with modifiers ANY, SOME and ALL. SQL-92
The axis here needs some explanation. Ale yak zavzhdi, on the cob butt What does it mean ALL in to this particular type? And it means the faults of those that are satisfied with the mental selection of those rows, the identifiers of which (our score is 4 and 5), more whatever from the knowledge of the value of pidzapit (1, 2 and 3). 4 more lower 1 і 2 і 3. 5 similar. What will be, what will we replace ALL on the ANY?What does it mean ANY in this vpadka? And it means the faults of those who satisfy the mental choice of those rows, the identifiers of which (in our case tse 2, 3, 4 and 5), more I would like one from the knowledge of the value of pidzapit (1, 2 and 3). For myself, I associate ALL h AND, a ANY h OR. SOMEі ANY analogues among themselves.
8. Operators of work with/with requests. SQL-92
Ask for help, what you can drink 2 among yourself for help of operators UNION or UNION ALL. Cym koristuyutsya often. Ale, use 2 more operators EXCEPTі INTERSECT.Butt from EXCEPT
In addition to the first multiplier, the data of the other multiplier are included.
Vlasne vіdbuvaєtsya peretin first multiplier value and other multiplier.
On tsimu everything, dyakuyu for your respect.
Editorial
N1. Dear streetflush for constructive criticism. Introduced the article information about those that are the standard of the movie, and which are not.N2. Item 4 has been corrected to clarify that ts/d/t is not part of the SQL mov. Thanks for the respect Melkij.
The INTERSECT operator draws identical rows from the result sets in one or more queries. For the first time, the INTERSECT operator is also thrown into an INNER JOIN.
INTERSECT belongs to the set operator class. Other such operators include EXCEPT and UNION. All operators for datasets are victorious for one-hour manipulation of the result sets of two and more inputs, the names of which are named.
Syntax SQL2003
There are no technical restrictions on the number of drinks in the INTERSECT operator. Hot syntax is coming.
INTERSECT
]INTERSECT
Keywords
Rows that are duplicated are included from the resulting sets.
DISTINCT
Rows, which are duplicated, are seen from the rest of the result sets before the rows, carried out by the INTERSECT operator. Empty (NULL) values are entered such that they are duplicated. If neither the keyword ALL nor DISTINCT is specified, then the abbreviation may be used for DISTINCT.
CORRESPONDING
It is indicated that less than these words can be rotated, so that they can appear in both queries with the same name, so that in both queries the key character (*) is victorious.
It is shown that only the names of the stompts are turned, so that they can be used to show other stompts with the most common names. Tsya proposition is to win at once with the key word CORRESPONDING.
Global rules
There is only one important rule, as it is necessary to remember every hour of work with the INTERSECT operator.
The order of that number of articles in all requests can be the same. Types of data in vіdpovіdnyh stovptsіv also may buti sumіsnі.
For example, CHAR types and VARCHAR sums. Behind the locking for the resultant set in the dermal stump, a rosemary will be drawn, which corresponds to the greatest type of dermal specific position.
The same platform does not support the CORRESPONDING proposition.
Appropriate to the ANSI standard, the INTERSECT operator may have higher priority over other operators for work sets, although on different platforms the priority of such operators is handled differently. You can clearly see the priority of the operators, vicarist arches. In a different way, the DBMS can move them in the right order, or from the first to the last.
Appropriate to the ANSI standard, a request can win only one proposition of ORDER BY. Put yoga in the box the rest of the instructions SELECT. In order to eliminate the ambiguity in the statements of the columns and the table, obov'yazkovo attach the very pseudonym to the table. For example:
On platforms that do not support the INTERSECT operator, you can replace it with FULL JOIN.
SELECT a.au_lname AS "lastname", a.au_fname AS "firstname" FROM authors AS a INTERSECT SELECT e.emp_lname AS "lastname", e.emp_fname AS "firstname" FROM employees AS e ORDER BY lastname, fir
Skills of types of data in different requests of the INTERSECT operator can be summed up, different RDBMS platforms can include different options of work with different values. For example, if aujname is the first entry in the front butt, it is significantly longer than the empjname entry from the other entry, different platforms can set different rules for determining the end result. Ale, vzagalі kazhuchi, platforms vybiratimut for the result dow (i less obmezheniya) expansion.
A skin RDBMS can set its own rules based on the name of the column in different instances, so that the names of the lists of columns may differ. Ring out the vikoristovuyutsya names of the stovpchikiv of the first request.
DB2
DB2 platform supported keywords INTERSECT and INTERSECT ALL to the ANSI standard plus the additional proposition VALUES.
(instruction._SELECT_7 | VALUES (elevation7 [, ...])) INTERSECT
] (Instruction_SCJ_2 | VALUES (elevation2 [, ...])) INTERSECT
Although the INTERSECT DISTINCT instruction is not supported, the functional equivalent is INTERSECT. The proposition CORRESPONDING is not supported.
In addition, the data types LONG VARCHAR, LONG VARGRAPHIC, BLOB, CLOB, DBCLOB, DATALINK and these structural types cannot be stuck with the INTERSECT word, but they can be matched with the INTERSECT ALL word.
If in the resulting data set there is a column that can have the same name in all SELECT statements, then it will win over as the remaining name for the statement to be rotated. If there are different names for the spat, the DB2 platform generates new names for the resulting spat. For the following reason, it becomes unsuitable for typing in the propositions ORDER BY and FOR UPDATE.
If in one request there is a small number of operators for work with sets of data, then the first one wins the one that is avenged in the arms. After that, the order of vikonnanny will be left. For example, all INTERSECT statements are converted to UNION and EXCEPT statements, for example:
SELECT empno FROM employee WHERE workdept LIKE "E%" INTERSECT (SELECT empno FROM emp_act WHERE projno IN ("IF1000", "IF2000", "AD3110") UNION VALUES ("AA0001"), ("AB00)"))
In the above application, from the employee table, the identifiers (ID) of all employees that work at the department, naming which starts with "E", are displayed. However, identifiers are more likely to appear in that case, as the stench is also found in the table of public records of service providers with the names emp_act and take part in the projects IF1000, IF200" and AD3110.
There is only one important rule of thumb using the EXCEPT instruction, as a reminder.
The order, the number of types of data, may be the same type for all requests.
Conforming to the ANSI standard, the UNION and EXCEPT set operators can still take precedence, but the INTERSECT statement overrides other set operators. We recommend that you explicitly take the priority of operators, vicorist arches. Tse vzagali є arcana practice.
Appropriate to the ANSI standard, a request can win only one proposition of ORDER BY. Insert yoga at the end of the rest of the SELECT statement. In order to eliminate the ambiguity in the statements of the columns and the table, obov'yazkovo attach the very pseudonym to the table. For example:
SELECT au_lname AS "lastname", au_fname AS "firstname" FROM authors EXCEPT SELECT emp_lname AS "lastname", emp_fname AS "firstname" FROM employees ORDER BY lastname, firstname;
In addition, the shards in the skin list of stovptsіv stovptsі can be indicated by different types of data, different RDBMS platforms can show different options for working with different types of data. For example, as the au_lname entry from the first entry in the front butt is significantly longer, the lower entry of emp_lname from the other entry, different platforms can stop different rules for determining the end result. Ale, vzagalі kazhuchi, platforms vybiratimut for the result dow (i less obmezheniya) expansion.
A skin RDBMS can set its own rules based on the name of the column in different instances, so that the names of the lists of columns may differ. The vipadku vikoristovuyutsya the names of the stovptsіv of the first request.
Types of data are not obov'yazkovo can be identical, but they are guilty but summіsnі. For example, CHAR types and VARCHAR sums. Behind the locking for the resultant set in the dermal stump, a rosemary will be drawn, which corresponds to the greatest type of dermal specific position. For example, a query that takes data from the parameters that will replace the values of the VARCHAR (IO) and VARCHAR (15) types, will win the VARCHAR (15) type and expansion.
However, the platforms do not support the proposition CORRESPONDING )) EXCEPT
(SELECT statemenr.2 | VALUES (expressionl, expression2 [, ...])) EXCEPT
Allows you to specify one or more columns, which are set manually, to be included in the residual result set. (It is called a row constructor.) The VALUES proposition may have the same number of columns, the number of rows can be specified in the EXCEPT statement. Although the EXCEPT DISTINCT statement is not supported, the functional equivalent is EXCEPT. The proposition CORRESPONDING is not supported. In addition, the data types LONG VARCHAR, LONG VARGRAPHIC, BLOB, CLOB, DBCLOB, DATALINK and these structural types cannot be stuck with the EXCEPT keyword, but they can be matched with the EXCEPT ALL keyword.
If in the resulting data set there is a column that can have the same name in all SELECT statements, then it will win over as the remaining name for the statement to be rotated. If this item is named differently in different SELECT statements, then you are responsible for changing the item in all queries, having the same AS alias proposition in all of them.
If in one request there is a small number of operators for work with sets of data, then the first one wins the one that is avenged in the arms. After that, the order of vikonnanny will be left. All INTERSECT statements are converted to UNION and EXCEPT statements. For example:
SELECT empno FROM employee WHERE workdept LIKE "E%" EXCEPT SELECT empno FROM emp_act WHERE projno IN (TF1000", TF2000", -AD3110") UNION VALUES ("AA0001"), ("AB0002" ;
In the above application, in the employee table, the identifiers (ID) of all the employees that work in the department, naming which one is based on "E", are included in the table of public records of the employees (emp_act), the IDs of those who are employed in the projects IF1000, IF200" and AD31 I have arrived, three additional IDs are added - AA0001, AB0002 and AC0003 for the assistance of the operator of the robot with UNION sets.
MySQL
MySQL does not support the EXCEPT statement. As an alternative, you can win the operations NOT IN or NOT EXISTS.
in tsyumu initial assistant you know how to win EXCEPT statement in SQL Server
(Transact-SQL) Syntax and Applications.
Description
SQL Server EXCEPT Statement(Transact-SQL) is rotated to rotate all rows in the first SELECT statement, if not rotated by another SELECT statement. The skin SELECT instruction is significant for data collection. The EXCEPT statement inspects all records in the first data set, and then inspects the results of all records in another data set.
Request Except
Explanation: Request EXCEPT to turn the record into a gray shade. The same records as are found in SELECT 1 and not in SELECT 2.
The SELECT statement in the EXCEPT query is responsible for the same number of fields in result sets with similar data types.
Syntax
The syntax for the EXCEPT statement in SQL Server (Transact-SQL) is:
Parameters chi arguments
expressions - columns or counts, as it is necessary to compare between two SELECT statements. The stench is not to blame but the same fields in the skin SELECT statement, but the stench is not to blame but with similar data types.
tables - tables, from which it is necessary to take records. Might want to use one table, listed in the FROM statement.
WHERE conditions - non-viscous. Wash up, as it is necessary to viconate for selected records.
Note
- Both SELECT statements can have the same number of entries.
- The types of data in the skin operator SELECT due to the mother are similar.
- The EXCEPT statement rotates all records from the first SELECT statement that do not appear before another SELECT statement.
- The EXCEPT operator in SQL Server is equivalent to the MINUS operator in Oracle.
An example with one viraz
Let's take a look at an example of an EXCEPT statement in SQL Server (Transact-SQL) that turns one field over the same data type.
For example:
Transact SQL
SELECT product_id FROM products EXCEPT SELECT product_id FROM inventory;
SELECT product_id FROM products SELECT product_id FROM inventory; |
This application of the EXCEPT statement rotates all product_id values that are in the products table and not in the inventory table. This means that although the product_id value is valid in the products table and the product_id value is valid in the inventory table, the product_id value is not displayed in the results of the EXCEPT query.
Butt with dekilcoma virazami
Then let's take a look at the application of EXCEPT SQL Server (Transact-SQL), which turns more than one column.
For example:
Transact SQL
In this application, EXCEPT rotates records in the contacts table with the names contact_id, last_name and first_name, as it does not match the values of employee_id, last_name and first_name in the employees table.
