Oracle中char类型与varchar2类型的区别，描述正确的是（）
A. char为定长字符数据类型
B. char为不定长字符数据类型
C. varchar2为定长字符数据类型
D. varchar2为不定长字符数据类型
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ORACLE中char类型与varchar2类型的区别，描述正确的是（）
A.char为定长字符数据类型 B.char为不定长字符数据类型 C.varchar2为不定长数据类型 D.char与varchar2没有区别 E.varchar2为定长数据类型
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Oracle中char类型与varchar2类型的区别，描述正确的是（）
A.char为定长字符数据类型 B.char为不定长字符数据类型 C.varchar2为定长字符数据类型 D.varchar2为不定长字符数据类型
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oracle中VARCHAR2类型的最大长度是（）
A.3000 B.4000 C.1000 D.2000
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The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) Which statement finds the rows in the CUSTOMERS table that do not have a postal code? （）
A.SELECT customer_id, customer_name FROM customers WHERE postal_code CONTAINS NULL; B.SELECT customer_id, customer_name FROM customers WHER postal_code = ' ___________'; C.SELECT customer_id, customer_name FROM customers WHERE postal _ code IS NULL; D.SELECT customer_id, customer_name FROM customers WHERE postal code IS NVL; E.SELECT customer_id, customer_name FROM customers WHERE postal_code = NULL;
答案
The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) The CUSTOMER_ID column is the primary key for the table. Which two statements find the number of customers?（）
A.SELECT TOTAL(*) FROM customer; B.SELECT COUNT(*) FROM customer; C.SELECT TOTAL(customer_id) FROM customer; D.SELECT COUNT(customer_id) FROM customer; E.SELECT COUNT(customers) FROM customer; F.SELECT TOTAL(customer_name) FROM customer;
答案
Examine the description of the CUSTOMERS table: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) The CUSTOMER_ID column is the primary key for the table. Which statement returns the city address and the number of customers in the cities Los Angeles or San Francisco?（）
A.SELECT city_address, COUNT(*) FROM customers WHERE city _ address IN ('Los Angeles','San Fransisco'); B.SELECT city_address, COUNT (*) FROM customers WHERE city address IN ( 'Los Angeles', 'San Fransisco') GROUP BY city_address; C.SELECT city_address, COUNT(customer_id) FROM customers WHERE city_address IN ( 'Los Angeles', 'San Fransisco') GROUP BY city_address, customer_ id; D.SELECT city_address, COUNT (customer_id) FROM customers GROUP BY city_ address IN ('Los Angeles','San Fransisco');
答案
The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER(4) NOT NULL CUSTOMER_NAME VARCHAR2(100) NOT NULL STREET_ADDRESS VARCHAR2(150) CITY_ADDRESS VARCHAR2(50) STATE_ADDRESS VARCHAR2(50) PROVINCE_ADDRESS VARCHAR2(50) COUNTRY_ADDRESS VARCHAR2(50) POSTAL_CODE VARCHAR2(12) CUSTOMER_PHONE VARCHAR2(20) The CUSTOMER_ID column is the primary key for the table. You need to determine how dispersed your customer base is. Which expression finds the number of different countries represented in the CUSTOMERS table?（）
A.OUNT(UPPER(country_address)) B.OUNT(DIFF(UPPER(country_address))) C.OUNT(UNIQUE(UPPER(country_address))) D.OUNT DISTINCT UPPER(country_address) E.OUNT(DISTINCT (UPPER(country_address)))
答案
The CUSTOMERS table has these columns: CUSTOMER_ID NUMBER (4) NOT NULL CUSTOMER_NAME VARCHAR2 (100) NOT NULL STREET_ADDRESS VARCHAR2 (150) CITY_ADDRESS VARHCAR2 (50) STATE_ADDRESS VARCHAR2 (50) PROVINCE_ADDRESS VARCHAR2 (50) COUNTRY_ADDRESS VARCHAR2 (50) POSTAL_CODE VARCHAR2 (12) CUSTOMER_PHONE VARCHAR2 (20) The CUSTOMER_ID column is the primary key for the table. You need to determine how dispersed your customer base is. Which expression finds the number of different countries represented in the CUSTOMERS table?（）
A.OUNT(UPPER(country_address)) B.OUNT(DIFF(UPPER(country_address))) C.OUNT(UNIQUE(UPPER(country_address))) D.OUNT DISTINTC UPPER(country_address) E.OUNT(DISTINTC (UPPER(country_address)))
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SQLite无法接收varchar(n)、char(n)、decimal(p,s) 等数据类型。
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Evaluate the set of SQL statements: CREATE TABLE dept (deptno NUMBER(2), dname VARCHAR2(14), loc VARCHAR2(13)); ROLLBACK; DESCRIBE DEPT What is true about the set?（）
A.The DESCRIBE DEPT statement displays the structure of the DEPT table. B.The ROLLBACK statement frees the storage space occupied by the DEPT table. C.The DESCRIBE DEPT statement returns an error ORA-04043: object DEPT does not exist. D.The DESCRIBE DEPT statement displays the structure of the DEPT table only if there is a COMMIT statement introduced before the ROLLBACK statement.
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下面关于char(4)与varchar(4)的说法中,正确的是
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