Using union and order by clause in mysql
You can do this by adding a pseudo-column named rank to each select, that you can sort by first, before sorting by your other criteria, e.g.:
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INSERT VALUES WHERE NOT EXISTS
You could do this using an IF statement: You could do it without IF using SELECT Both methods are susceptible to a race condition, so while I would still use one of the above to insert, but you can safeguard duplicate inserts with a unique constraint: Example on SQL-Fiddle ADDENDUM In SQL Server 2008 or later you can use MERGE with HOLDLOCK to remove the … Read more
“select * into table” Will it work for inserting data into existing table
You should try Have a look at INSERT and SQL SERVER – Insert Data From One Table to Another Table – INSERT INTO SELECT – SELECT INTO TABLE
ORA-01779: cannot modify a column which maps to a non key-preserved table
A DML table expression clause is only useful when you need columns from more than one table. In your case, you can use a regular update with an EXISTS: If you really do need to use columns from both tables you have three options: repeat the join in the SET and the WHERE clause. This is easy to build but … Read more
Is merge statement available in MySQL
MERGE is not supported by MySQL, However, there is other possible way of doing the same: INSERT…ON DUPLICATE KEY UPDATE If you specify the ON DUPLICATE KEY UPDATE option in the INSERT statement and the new row causes a duplicate value in the UNIQUE or PRIMARY KEY index, MySQL performs an update to the old row … Read more
SQL Server – An expression of non-boolean type specified in a context where a condition is expected, near ‘RETURN’
That is invalid syntax. You are mixing relational expressions with scalar operators (OR). Specifically you cannot combine expr IN (select …) OR (select …). You probably want expr IN (select …) OR expr IN (select …). Using union would also work: expr IN (select… UNION select…)
How to order by column A and then by column B?
The SQLite website has syntax diagrams explaining the SQL grammar supported by SQLite.
Append table to an existing one: SQL Server
The basic form is: This may not work if, for instance, you have a unique constraint on the columns and the insert violates this constraint. This assumes that you actually want to add the rows to the table. If you just want to see the results together: EDIT: The goal seems to be to add columns one tableB. … Read more
How do I view the Explain Plan in Oracle Sql developer?
EXPLAIN PLAN FOR In SQL Developer, you don’t have to use EXPLAIN PLAN FOR statement. Press F10 or click the Explain Plan icon. It will be then displayed in the Explain Plan window. If you are using SQL*Plus then use DBMS_XPLAN. For example, See How to create and display Explain Plan
How to truncate the text returned for a column in a MySQL query
Quoting mysql.com: For all forms of SUBSTRING(), the position of the first character in the string from which the substring is to be extracted is reckoned as 1.