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drop table computer_terms;
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ERROR: Relation 'computer_terms' does not exist
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create table computer_terms(term text, category text, comments char(16));
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create index computer_terms_index1 on computer_terms using btree(term);
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create index computer_terms_index2 on computer_terms using btree(category);
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insert into computer_terms values('computer display', 'X-A01-Y', 'a comment 1');
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insert into computer_terms values('computer graphics', 'T-B01-Y', 'a comment 2');
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insert into computer_terms values('computer programmer', 'S-Z01-Y', 'a comment 3');
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select * from computer_terms;
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term | category | comments
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---------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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computer graphics | T-B01-Y | a comment 2
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computer programmer | S-Z01-Y | a comment 3
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select * from computer_terms where category = 'X-A01-Y';
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term | category | comments
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------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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select * from computer_terms where category ~* 'x-a01-y';
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term | category | comments
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------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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select * from computer_terms where category like '_-A01-_';
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term | category | comments
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------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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select * from computer_terms where category like '_-A%';
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term | category | comments
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------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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select * from computer_terms where term ~ 'computer [dg]';
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term | category | comments
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-------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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computer graphics | T-B01-Y | a comment 2
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select * from computer_terms where term ~* 'computer [DG]';
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term | category | comments
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-------------------+----------+------------------
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computer display | X-A01-Y | a comment 1
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computer graphics | T-B01-Y | a comment 2
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select *,character_length(term) from computer_terms;
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term | category | comments | char_length
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---------------------+----------+------------------+-------------
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computer display | X-A01-Y | a comment 1 | 16
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computer graphics | T-B01-Y | a comment 2 | 17
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computer programmer | S-Z01-Y | a comment 3 | 19
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select *,octet_length(term) from computer_terms;
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term | category | comments | octet_length
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---------------------+----------+------------------+--------------
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computer display | X-A01-Y | a comment 1 | 16
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computer graphics | T-B01-Y | a comment 2 | 17
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computer programmer | S-Z01-Y | a comment 3 | 19
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select *,position('s' in term) from computer_terms;
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term | category | comments | strpos
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---------------------+----------+------------------+--------
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computer display | X-A01-Y | a comment 1 | 12
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computer graphics | T-B01-Y | a comment 2 | 17
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computer programmer | S-Z01-Y | a comment 3 | 0
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select *,substring(term from 10 for 4) from computer_terms;
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term | category | comments | substr
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---------------------+----------+------------------+--------
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computer display | X-A01-Y | a comment 1 | disp
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computer graphics | T-B01-Y | a comment 2 | grap
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computer programmer | S-Z01-Y | a comment 3 | prog