Using SQL, how would you select all the records from a table called "Personas", where the "Nombre" is "Pedro" and the "Apellido" is "Gil"?
Select one: SELECT * WHERE Nombre = 'Pedro', Apellido = 'Gil' FROM Personas; SELECT * FROM Personas WHERE Nombre LIKE 'Pedro' AND Apellido LIKE 'Gil'; SELECT * FROM Personas WHERE Nombre = 'Pedro' OR Apellido = 'Gil'; SELECT * FROM Personas WHERE Nombre LIKE 'Pedro' AND LIKE 'Gil';.
Which of these statements is correct about the following query?
SELECT DNOMBRE 'DEPARTAMENTOS', DEPT_NO 'NUMERO DEPARTAMENTO' FROM DEPART;
Select one: Column aliases are specified with * It is correct that aliases are allowed in columns Column aliases are specified before the column name Aliases are not allowed in columns.
Which of these statements about the sentence SELECT are true?
Select one or more: We can get any row, all rows, any subset of rows from a table. It is used to retrieve information. It is part of the Data Definition Language statements. It is used to make queries to the Database.
Choose which of the following rules for compositions are true:
Select one or more: As many tables as desired can be combined. The combination criterion can be made up of more than one pair of columns. SELECT Columns from both tables can be cited in the clause , whether or not they condition the combination. If there are columns with the same name in different tables, it is not necessary to identify them by specifying the table of origin, since they should have different names.
In the syntax of SELECT, the clause ALL:
Select one: Retrieves all rows even if they are repeated. Retrieves all columns even if they are repeated. Retrieves all columns from the specified table. Retrieves all rows that are not repeated.
In a sentence SELECT the mandatory clauses are:
Select one: SELECT, FROM SELECT, FROM, WHERE, ORDER BY SELECT, FROM, WHERE SELECT, FROM, WHERE GROUP BY.
HAVING and WHERE:
Select one: HAVING validates group conditions. WHERE ask about group characteristics. They are equivalent clauses, they are used in the same way. HAVING asks for characteristics of specific rows.
The function : REPLACE ('QUE COMPLEJO ES SQL', 'SQL', 'sql'). What string would it return?
Select one: qUE COMPlEJo Es sql que complejo es SQL QUE COMPLEJO ES sQl QUE COMPLEJO ES sql.
The syntax of the subqueries is as follows:
SELECT listaExpr FROM tabla WHERE expresión OPERATOR ( SELECT listaExpr FROM tabla);
Which of the following operators can we use as OPERATOR?
Select one or more: OR = IN >.
MySQL has several data types to handle dates, select an option:
Select one: VARCHAR, SYSDATE DATE, DATETIME,TIMESTAMP DOUBLE DATE, BLOB.
To obtain data from two tables, Comerciales y Anuncios, the query must be:
Select one: SELECT COMERCIALES FROM ANUNCIOS; SELECT * FROM COMERCIALES AND ANUNCIOS; SELECT * FROM COMERCIALES GROUP BY ANUNCIOS; SELECT * FROM COMERCIALES, ANUNCIOS WHERE COMERCIALES.DNI = ANUNCIOS.DNI_COMERCIAL;.
What is the clause for GROUP BY?
Select one: Specify the condition that a group of rows must meet. Organize records into groups and get a summary of those groups. Classify the selected fields in an orderly manner. Group the columns of a table.
What would the following query return SELECT ABS(-32);?
Select one: -32 32 Ninguna de las demás es correcta. 5.
What would the following query return?
SELECT LAST_DAY('2023-01-05');
Select one: 01/31/22 Wednesday Thursday 2023-01-31.
What does the following query return in MySQL?
SELECT TRUNCATE(187.98,0);
Select one: 187.1 187 187.100 188.
What is an external composition?
Select one or more: Select rows from one table even if they do not correspond to rows from the other table. OUTER JOIN MINUS JOIN.
What keyword is used to return only different values?
Select one: AS COUNT DISTINCT ORDER BY.
What keyword is used to sort the result?
Select one: ORDER SORT ASC ORDER BY.
What value does the function?
return in MySQL SELECT INSTR("W3Schools.com", "com");
Select one: 6 2 10 11.
I want to extract the last character of a string, to do this I would use:
Select one: INSTR('cadena',-1) SUBSTR('cadena', length('cadena')) SUBSTR('cadena', 1,-1) INSTR('cadena', length('cadena')).
What function would you use to convert a string of characters to uppercase?
Select one: UPPER TRIM TO_CHAR LOWER.
I want to fill the Locality column with periods ("...") on the right, and with a total length of 30 characters.
To do this I would use: LPAD(Localidad, 30, '.') RPAD(Localidad, 30, '.') RPAD(Localidad, length(localidad)+30, '.') RPAD(Localidad, length(localidad)+12, '.').
If you examine the SELECT rows of table A and table B and obtain those rows that appear in both tables, eliminating duplicates.
You are using: MINUS JOIN UNION INTERSECT.
If using string comparison operators I want to get any string whose second character is an A.
I would use: _A' '%A%' '_A%' '_ _ A%'.
We have the following query
SELECT COUNT(*) FROM EMPLEADOS GROUP BY DEPARTAMENTOS;
What result would we obtain? Number of employees in each department. Number of total employees. Number of total rows in the table. Number of columns in the EMPLOYEES table grouped by departments.
We have the following query:
SELECT DEPT_NO FROM DEPART WHERE LOC=('MADRID', 'BARCELONA');
Which of the following answers is true?
Select one: It is not correct, you must leave a space between LOC and the equals symbol. It is not correct because MADRID and BARCELONA must be written with double quotes. It is not correct because you have to use the 'IN' operator instead of the = It's correct. The final ; is not necessary.
When does a statement SELECT alter the content of a table?
Select one: Never, SELECT does not alter the content of a table. Only if calculations are involved ( SUM, AVG). Only when it affects all records. Always.
The external join (OUTER JOIN) allows us to select some rows from a table even if they do not correspond to the rows of the other table with which it is combined.
True or false? True False.
The MAX(expression) function returns the maximum value of the expression considering nulls.
True or false? True False .
Subqueries only appear as part of the search condition of a WHERE clause, never of HAVING clauses, which is inherent to GROUP BY.
True or false? True False .
Match each definition with its related SQL statement: Undo changes to a transaction since it was started. Establish an intermediate restore point. Make changes produced by a transaction permanent. Undo changes to a transaction from a restore point. .
Match each definition with its related term: The transaction starts from a consistent state of the data and ends leaving it with consistent data as well. All tasks in a transaction are performed correctly, or if not, none of them are performed. The effect of a transaction is not visible to other transactions until it ends. The changes made by the transactions that have dumped their modifications become permanent. .
Match the lock type definitions with their description: They protect the schema definition of an object while an operation acts on it. They protect data, guaranteeing the integrity of data accessed concurrently by multiple users. They protect the internal database and memory structures. .
When modifying or assigning the value of a field that is a foreign key, what possible values can be established?
Select one: Only values that are not contained in the primary key of the reference table. Only values contained in the primary key of the reference table. Any value of the same type as the primary key of the reference table. Any value of any type.
How is a transaction defined?
Select one: Set of SQL statements that can be executed in phases. Dumping data from one database to another. An atomic unit of work that contains one or more SQL statements. Dumping data from one table to another.
Which of the following statements about locks between reader and writer users are correct?
Select one or more: A record is locked only when it is modified by a writer. A writer always blocks a reader. A writer of a record blocks another concurrent writer of the same record. A reader always blocks a writer.
Which of the following operations make changes produced by a transaction permanent?
Select one or more: Properly close the database management application. Execute a DDL statement . Use the statement UPDATE. Use the statement COMMIT.
What is the correct format of the statement DELETE in SQL ?
Select one: DELETE SET nombre_tabla [ WHERE condición ]; DELETE INTO nombre_tabla [ SET condición ]; DELETE FROM nombre_tabla [ WHERE condición ]; DELETE nombre_tabla [ FROM condición ];.
What is the correct format of the statement INSERT in SQL?
Select one: INSERT INTO nombre_tabla (lista_campos) SET (lista_valores); INSERT INTO nombre_tabla (lista_campos) VALUES (lista_valores); INSERT FROM nombre_tabla (lista_campos) VALUES (lista_valores); INSERT FROM nombre_tabla (lista_campos) WHERE (lista_valores);.
What is the correct format of the statement UPDATE in SQL ? UPDATE nombre_tabla INTO nombre_campo \ = valor [, nombre_ campo = valor]...[ WHERE condición ]; UPDATE FROM nombre_tabla SET nombre_campo = valor [, SET nombre_ campo = valor]...[ WHERE condición ]; UPDATE nombre_tabla SET nombre_campo \ = valor [, nombre_ campo = valor]...[ FROM condición ]; UPDATE nombre_tabla SET nombre_campo \ = valor [, nombre_ campo = valor]...[ WHERE condición ];.
What is the meaning of cascade deletion?
Select one: If an attempt is made to delete a record in the reference table that is being referenced from another table, an error occurs in the deletion operation, preventing said action. When you delete records from the reference table, the records in the child table that referenced those records are also deleted. When you delete records from the reference table, all records in the child table are also deleted. The values of the foreign key that referred to the records that have been deleted from the reference table are changed to the value NULL.
Is it possible to partially undo changes made by a transaction?
Select one: No, it is impossible to undo any type of change ordered in a transaction. Yes, executing the order to undo all changes to the transaction. Yes, setting a restore point and executing the command to undo the changes up to that point. No, only all operations contained in the transaction can be undone.
The first transaction that performs a _____ is the only transaction that can modify the resource until the lock is released.
Select one: concurrent locking consistent blocking exclusive lock shared lock.
To make a manual block of a complete record in a table, use the SQL statement :
Select one: SELECT … FOR UPDATE UPDATE … FOR SELECT LOCK TABLE … TABLE … FOR UPDATE.
Which character should be used in the SQL statement INSERTto separate the values in the list of values ?
Select one: comma Semicolon dot Space.
What is the name of the property in which the foreign key values of one table always correspond to a value of the primary key of another table.
Select one: Integridad referencial Bloqueo compartido Concurrencia de datos Consistencia de datos.
What term defines the fact that data being viewed or modified by a user cannot be changed by others until the user has completed the entire operation?
Select one: Reference Integrity Concurrence Consistency.
If when inserting a new record or editing the data of an existing one you try to type a letter in a numeric field, what happens when you try to save the data?
Select one: You get an error and no change occurs. There is no notice. This must be verified by the user. That value is saved with the value null. You get an error but all other correct data changes are saved.
If a condition is not indicated in the statement DELETE, what happens?
Select one: All records in the table are deleted. An error occurs. Only the first record is deleted from the table. Nothing happens.
If a condition is not indicated in the statement UPDATE, what happens?
Select one: Nothing happens. Only the data of the first record in the table is modified. An error occurs. All records in the table are modified to the new values indicated.
In the pessimistic lock, this is carried out immediately, as soon as the lock is requested.
True or false? True False.
In the SQL INSERT statement , is it mandatory to indicate all the fields of the table?
True or false? True False .
To execute a SQL statement from the "Execute SQL Command Line" application, is it necessary to previously connect to the database indicating the username and password?
True or false? True False.
Can more than one user access the same database simultaneously?
True or false? True False.
Can you indicate in the primary key of a table a value that is not found in the foreign key of another table, both keys being the ones that relate the two tables?
True or false? True False.
If an application fails and terminates unexpectedly, and was in the middle of processing a transaction, are the changes made to the transaction up to that point made permanent?
True or false? True False .
|
