Task $8$: Using the INVOICE$\_$TOTAL VIEW write and execute the command to retrieve the invoice number and invoice total for only those orders totaling more than $$250.$

Task $9$: Repeat Task $8$ without using the INVOICE$\_$TOTAL VIEW.

Task $10$: List all the tables contained within the system catalog, but only display the first $10$ records with a TABLE$\_$TYPE of SYSTEM VIEW.

Task $11$: List all the columns contained within the system catalog, but only display the first $11$ records that are in the KimTay TABLE$\_$SCHEMA.

Task $12$: List all the views contained within the system catalog, but only display the first $12$ records.

Task $13$: Write the command to display only tables within the system catalog that have the KimTay TABLE$\_$SCHEMA and are of the type BASE TABLE. Display only the following columns: TABLE$\_$SCHEMA, TABLE$\_$NAME, TABLE$\_$TYPE.

Task $14$: Create an index named ITEM$\_$INDEX$1$ on the ITEM$\_$ID column in the INVOICE$\_$LINE table.

Task $15$: Create an index named ITEM$\_$INDEX$2$ on the CATEGORY column in the ITEM table.

Task $16$: Create an index named ITEM$\_$INDEX$3$ on the CATEGORY and LOCATION columns in the ITEM table.

Task $17$: Create an index named ITEM$\_$INDEX$4$ on the CATEGORY and LOCATION columns in the ITEM table. List categories in descending order.

Task $18$: Delete the index named ITEM$\_$INDEX$3.$

Task $19$: List every table that you have created thus far. Display the TABLE$\_$SCHEMA and TABLE$\_$NAME columns.

Task $20$: List every column in the ITEM table and its associated data type.

Task $21$: Alter the INVOICE$\_$LINE table by adding the INVOICE$\_$NUM column as a foreign key referencing the INVOICE$\_$NUM column in the INVOICES table. From The Textbook of A Guide to SQL $10$th edition