112 lines
4.0 KiB
MySQL
112 lines
4.0 KiB
MySQL
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create or replace function altercolumn(tablename name, columnname name, datatype name,
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nullclause varchar, defaultclause varchar) returns void as $$
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declare
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command text;
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viewtext text[];
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viewname name[];
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dropviews name[];
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i int;
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j int;
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v record;
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sqltype text;
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sqltype_short text;
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typename name;
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begin
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if datatype is not null then
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select pg_type.typname, format_type(pg_type.oid, pg_attribute.atttypmod)
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into typename, sqltype
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from pg_class, pg_attribute, pg_type
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where relname = lower(tablename)
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and relkind = 'r'
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and pg_class.oid = pg_attribute.attrelid
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and attname = lower(columnname)
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and atttypid = pg_type.oid;
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sqltype_short := sqltype;
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if typename = 'numeric' then
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sqltype_short := replace(sqltype, ',0', '');
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elsif strpos(sqltype,'character varying') = 1 then
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sqltype_short := replace(sqltype, 'character varying', 'varchar');
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elsif sqltype = 'timestamp without time zone' then
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sqltype_short := 'timestamp';
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end if;
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if lower(datatype) <> sqltype and lower(datatype) <> sqltype_short then
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i := 0;
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for v in select a.relname, a.oid
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from pg_class a, pg_depend b, pg_depend c, pg_class d, pg_attribute e
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where a.oid = b.refobjid
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and b.objid = c.objid
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and b.refobjid <> c.refobjid
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and b.deptype = 'n'
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and c.refobjid = d.oid
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and d.relname = lower(tablename)
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and d.relkind = 'r'
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and d.oid = e.attrelid
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and e.attname = lower(columnname)
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and c.refobjsubid = e.attnum
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and a.relkind = 'v'
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loop
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i := i + 1;
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viewtext[i] := pg_get_viewdef(v.oid);
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viewname[i] := v.relname;
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end loop;
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if i > 0 then
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begin
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for j in 1 .. i loop
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command := 'drop view ' || viewname[j];
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execute command;
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dropviews[j] := viewname[j];
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end loop;
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exception
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when others then
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i := array_upper(dropviews, 1);
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if i > 0 then
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for j in 1 .. i loop
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command := 'create or replace view ' || dropviews[j] || ' as ' || viewtext[j];
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execute command;
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end loop;
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end if;
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raise exception 'Failed to recreate dependent view';
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end;
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end if;
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command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' type ' || lower(datatype);
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execute command;
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i := array_upper(dropviews, 1);
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if i > 0 then
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for j in 1 .. i loop
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command := 'create or replace view ' || dropviews[j] || ' as ' || viewtext[j];
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execute command;
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end loop;
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end if;
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end if;
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end if;
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if defaultclause is not null then
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if lower(defaultclause) = 'null' then
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command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' drop default ';
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else
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command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' set default ''' || defaultclause || '''';
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end if;
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execute command;
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end if;
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if nullclause is not null then
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if lower(nullclause) = 'not null' then
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command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' set not null';
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execute command;
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elsif lower(nullclause) = 'null' then
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command := 'alter table ' || lower(tablename) || ' alter column ' || lower(columnname) || ' drop not null';
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execute command;
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end if;
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end if;
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end;
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$$ language plpgsql;
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/*
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create table t_alter_column
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( tablename name, columnname name, datatype name, nullclause varchar(10), defaultclause varchar(200));
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create rule alter_column_rule as on insert to t_alter_column
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do instead select altercolumn(new.tablename, new.columnname, new.datatype, new.nullclause,
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new.defaultclause);
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*/
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