[amp_mcq option1=”Foreign key fields don’t allow duplicate values” option2=”In primary key field you can enter duplicate value” option3=”In an indexed field you may or may not enter duplicate value depending upon setting” option4=”All statements are true” correct=”option1″]<\/p>\n
The correct answer is: A. Foreign key fields don’t allow duplicate values<\/strong><\/p>\n A foreign key is a column or group of columns in a table that refers to the primary key of another table. The foreign key column(s) must contain the same values as the primary key column(s) of the other table. This ensures that the data in the two tables is consistent.<\/p>\n A primary key is a column or group of columns in a table that uniquely identifies each row in the table. The primary key column(s) cannot contain duplicate values.<\/p>\n An index is a data structure that improves the performance of queries on a table. An index can be created on one or more columns in a table. The columns in an index must be unique, but they do not have to be the primary key columns.<\/p>\n Therefore, the only statement that is true is A.<\/p>\n","protected":false},"excerpt":{"rendered":" [amp_mcq option1=”Foreign key fields don’t allow duplicate values” option2=”In primary key field you can enter duplicate value” option3=”In an indexed field you may or may not enter duplicate value depending upon setting” option4=”All statements are true” correct=”option1″]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[672],"tags":[],"class_list":["post-16135","post","type-post","status-publish","format-standard","hentry","category-ms-access","no-featured-image-padding"],"yoast_head":"\n